965 0528 Onan BGE (spec F K) NHE E Genset Service Manual (09 1994) 1060 Supplement M) (11 1995)

User Manual: 965-0528 Onan BGE (spec F-K) NHE (spec E-K) Genset Service manual (09-1994) 965-1060 Supplement (spec M) (11-1995)

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BGE, NHE
Emerald Plus'"Series

.

I

,
965-0528
(BGE Spec F through K, NHE Spec E through K)
9-94

Redistribution or publication of this document
by any means, is strictly prohibited.

The engine exhaust from this product
contains chemicals known to the State
of California to cause cancer, birth
defects or other reproductiveharm.

Redistribution or publication of this document
by any means, is strictly prohibited.

,

Supplement 965-1060
Date: 11-95
Insert withTitle: BGE/NHE Service Manual
Number (Date): 965-0528 (9-94)

PURPOSE

SERVICE MANUAL 965-0528 REVISIONS

This Supplement supercedes Supplement
965-1055. It transmits the revisions to the Service
Manual necessaryfor covering all Spec Mgenerator sets: gasoline fueled and LPG fueled. Notethat
the nameplate on a Spec M generator set will have
the statement: “This engine meets 1995-1998
California emissions regulations for ULGE engines.”

1. Insert this Supplement in its entirety under
the front cover of the manual. (Discard any
.
copy of Supplement 965-1055.)

2. On Page 1-1 wriie: “See Operator’s Manualfor
fuel and engine oil recommendationsand Periodic Maintenance.”
3. On Page 2-1 write: “For Spec M and later, ignition timing (nonadjustable) is 12” BTDC.”
4. On Page 5-4 write: “See Page S-2 of Supple-

To satisfy California emissions regulations Spec M
generator sets have internal engine modifications
and precision-manufacturedcarburetors with tamper-resistantfuel mixturejets and tamper-resistant
LPG demand regulators. It should therefore be
noted that fuel mixture and LPG lock-off pressure
adjustments should not be attempted. Nor should
the carburetor or LPG demand regulator be overhauled. Instead, a malfunctioning carburetor or
LPG demand regulator should be replaced (see
TROUBLESHOOTING ENGINE PRIMARY SYSTEMS in Section 6).

ment 965-1060 for instructionson howto purge
LPG and disconnect the genset from RV systems.” Cross out the instructions under the
subheadings LP-Gas (Propane) Purging Procedure and Disconnecting Set from RV Systems on Page 5-4.
5. On Page 6-15 under the heading GOVERNOR, write: “See Supplement 965-1060 for
Spec M and Later.”
6. On Page 6-17 under the heading FUEL SYSTEM-GASOLINE, write: “See Supplement
965-1060 for Spec M and Later.”
7. On Page 6-25 under the heading FUEL SYSTEM-LPG LIQUID WITHDRAWAL, write:
“See Supplement 965-1060 for Spec M and
Later.”
8. On Page 6-31 under the heading FUEL SYSTEM-LPG VAPOR WITHDRAWAL, write:
“See Supplement 965-1060 for Spec M and
Later.”

LgWAR”G1 Unauthorized modifications or replacement of fuel, exhaust, air intake or speed
control system wmponenis that affecf engine
emissions are prohibited by law in the State of
California.
9

Modification, removal or replacement of the
generator set label is also prohibited,

I

I

The engine exhaust from this product
contains chemicals known to the State
of California to cause cancer, birth
defects or other reproductive harm.

s-I

Redistribution or publication of this document
by any means, is strictly prohibited.

Disconnecting Set from RV Systems
(All Specs)

sible, run the genset (ii it starts) until it runs out
of fuel with the LPG valve(s) closed.

jk
LPG is flammable and explosive and can cause asphyxiation. NFPA 58,
Section 1.6 requires all persons handling
LPG to be trained in proper handling and
operating procedures.

1. First disconnect the negative (-) battery cable
from the baitery and then disconnect the battery cables from the genset.

LQWAR”G1 Sparks and high current could
cause fire and other damage to the battery,
battery cables and vehicleif the loose ends
of cables connected to the battery touch.
Always disconnect the negative (-) battery
cable from the battery before disconnecting the battery cables from the genset.

a

LPG “sinks” when it escapes into the air
and can accumulate in explosive concentrations. Before disconnecting the LPG
fuel line, close the fuel shutoff valve(s) at
the LPG container(s) and move the vehicle
outside and away from pi& or basements or
other below-grade spaces where LPG
could accumulate.

2. Disconnect the remote control wiring harness
connector at the genset.

3. Disconnect the generator output wiring and
conduit from the power distribution panel or
box on the vehicle. Tag all wires to make reconnections easier.

ForLPG li9uid-wifhdrawalsyste~s
(see Figure
S-6) push the regulator priming button while
cranking for 10 seconds to purge some of the
remainingLPG. Then loosenthe threadedflexible fuel supply hose connector at the fuel filter
on the genset just enough to hear gas escaping. Unthreadthe connectorwhenno moregas
is heard escaping. Finally, cap the end of the
fuel supply hosewitha 1/4 inch NFTF pipe cap
to prevent fuel from escaping if someone inadvertently opens the shutoff valve(s) at the LPG
container(s).

4. Disconnectthe exhaust tailpipe from the outlet

of the muffler andthen removethe muffler. See
EXHAUST SYSTEM under Engine Subsystems.
5. Disconnectthe fuel linefrom thegenset. Follow
the applicable instructions depending on the
fuel.

[QWARNINGI Gasolineand LPG (liguifiedpe-

Large volumes of LPG can be
released in the process of disconnecting a
liquid-withdrawal type of LPG supply system. Before disconnecting LPG fuel connections, make sure the the fuel shutoff
valve@)at the LPG container(s) are closed
and that the vehicle is outside and away
from pits or basements or other belowgrade spaces where LPG could accumulate.

troleum gas) are flammable and explosive
and can cause severe personal injury or
death. Do not smokeif you smellgas orgasoline or are near fuel tanks or fuel-burning
equipment or are in an area sharing ventilation with such equipment. Keep flames,
sparks, pilot lights, electrical arcs and arcproducing equipment and all other sources
of ignition well away.
Gasoline Fueled Gensets: Disconnect the
fuel line from the genset and securely plug the
end of the fuel lineto prevent leakageor an accumulation of explosive gasoline vapor.

9

ForLPG vapor-withdrawalgensets(see Figure
S-IO) disconnect the gas supply hose at the
carburetor and the fuel solenoid shutoff valve
leads at the control box on the genset. If the
pressure regulator/solenoidvalve assembly is
also to be removed, cap the end of the fuel supply linewith athreaded pipe cap to preventfuel
from escaping if someone inadvertently opens
the shutoff valve(s).

f PG Fueled Gensets: Close the fuel shutoff
valve(s) at the LPG container(s) and move the
vehicle outside and away from below-grade
spaces where LPG could accumulate. To
purgethe fuel line and genset as much as poss-2

Redistribution or publication of this document
by any means, is strictly prohibited.

FUEL SYSTEM

Carburetor And Intake Manifold Assembly

(BEGINNING SPEC M)
The carburetor mixes air and fuel in the correct proportion for good performance. The governor operates the throttle to maintain a nearly constant engine speed (frequency) as the load vanes. Figure
S-1 is representative of most of the fuel system
parts. LPG (liquifiedpetroleumgas) systemsdo not
use an air preheateror choke and havedifferentfuel
connections. See Automatic Choke, Fuel Pump
and LPGSystemComponentsinthis sectionfor details of the other parts of the fuel system.

Disassembly:
1. Remove the air cleaner assembly.
2. Disconnectthe fuel line and governor rod from
the carburetor.

Large volumes of LPG can be
released in the process of disconnectinga
liquid-withdrawal fype of LPG supply system. See Disconnecting Set from RV Systems (Page S-2) for the proper procedures
and precautions.

1QWAR"GI Gasoline and LPG are flammable
and explosive and can cause severe personal
injury or death. Do not smokeif you smellgas or
gasoline vapors or are near fuel tanks or fuelburning equipment or are in an area sharing
ventilation with such equipment. Keep flames,
sparks, pilot flames, electrical arcs and
switches and other sources of ignition well
away.

3. Remove the intake manifold capscrews, the
carburetor air preheater (gasoline gensets
only) andthe carburetorand intakemanifoldas
an assembly. On LPG gensets equipped for
liquid withdrawal, if will first be necessary to
disconnect the fuel vaporizer (the tube
wrapped aroundthe exhaust manifold)at both
ends, remove the pressure regulator, disconnect the vaporizer line from.its support bracket
and rotate the vaporizer line out of the way.

1-b

LPG is flammable and explosive
and can cause asphyxiation. NFPA 58, Section
1.6 requires all persons handling LPG to be
trainedin proper handling and operatingprocedum.

Air Cleaner Assembly

1-

Bending the fuel vaporizer tu&
ing can weaken it to the point that it can
crack allowing LPG under high pressure to
escape, resulting in possible sever??personal injury or death.

Disassembly:
1. Remove the crankcase breather hose and air
preheater hose (gasoline gensets only) from
the air cleaner housing.

2. Remove the air cleaner housing center
capscrew and lift off the housing and air filter.

4. Remove the two intake manifold gaskets and
cover the intake ports to prevent loose parts
from accidentally entering the ports.

3. Remove the three capscrews that secure the
air cleaner adapter to the carburetor and lift off
the adapter. (One of the screws is inside the
throat of the adapter.)

5. Unboltthe carburetorfromthe intake manifold.

Reassembly: Reassembly is the reverse of disassembly. Use new gaskets betweenthe intake manifold and the engine and between the intake manifold and the carburetor. Do not use sealer on the
gaskets. Tighten all fasteners accordingto Assembly Torques.

Reassembly: Reassembly is the reverse of disassembly. Use a new gasket betweenthe adapter and
the carburetor.

1-

Takecarenot to cross-threadtheinside adapter mounting screw.

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O-RING

(Slip the O-ring over the end of the

HOSEAND CUP

is connected here through an elbow fitting)

FIGURE $1. TYPICAL FUEL SYSTEM

S-4

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by any means, is strictly prohibited.

Governor and Carburetor Adjustments

Consequentialdamage to W’s,VCR’s, computers and other voltage and frequency sensitive
devices as a result of failing to observe thisprecaution is nof covered under the Onan warranty
policy.

Careful adjustments of the carburetor and governor
are essential for top performance. Perform all necessary engine and generator maintenanceand repairs before making these adjustments.

Governor Rod Length AdjustrnenlThe length of
the governor rod (Figure S-2) must be checkedand
adjustedas follows beforeother adjustmentsare attempted:

These adjustments require the use of meters to
measure voltage, frequency and amperage and a
stepped load bank of at least 8 kW, where a portion
of at least 600 watts is variable. Digital meters are
recommended.Accuracy shouldbeat least 0.3 percent for frequency. measurement and 0.5 percent
for voltage measurement.

1. Loosen the lock nut at the ball joint end of the
governor rod and unsnap the socket from the
ball.
2. Push the governor rod gently towards the carburetor (full-throttle position). While keeping it
there, turn the socket, as necessary, to
lengthen or shorten the rod so that the ball and
socket line up.

It is recommendedthat the genset be disconnected
from the AC service panel of the vehicle. If the genset is not disconnected, disconnect or unplug all
voltage and frequencysensitivedevicesthroughout
the vehicle to protectthem from thevariationsin frequency and voltage that occur during these adjustments.

1-

Too much pressure on the rod
can result in a faulty adjustment of the rod
length.
3. Snap the socket back over the ball.
4. Tighten the lock nut while holding the socket
square with the axis of the ball. Also, the leg at
the throttle end of the rod must be kept level.
5. Gently rotate the governor arm and check for
.
binding. If necessary, loosen the locknut and
repeat Step4 untilthe linkagemovessmoothly.
Binding can cause erratic governor action.

1-b

Disconnect or unplug all voltage
and fwuency sensitive devices such as W’s,
VCR’s, computers and other solid-state electronic devicesbefom making governor and carburetor adjustments. Typicallly,some internal
cimujts are powered when these types of devicesarepluggedin,even if the devicehas been
switched ““OFF”, These circuits can be damaged by variations in voltage and frequency.

FIGURE S-2. GOVERNOR ROD

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by any means, is strictly prohibited.

Note: The following groups of adjustments must be
performed in sequence.

IDLESPEED
ST_OPSCREW

Idle Speed Stop Adjustment: The frequency
specificationsfor 60 Hz gensets are followed in parentheses by the specifications for 50 Hz gensets.
1. Start the genset and let it warm up for ten minutes under 1/2 to 3/4 rated load. (On vapor
withdrawal type LPG gensets it might be necessary to first adjust the supply pressure as instructed under LPG System Components to
get the genset to start.)
2. Disconnectthe load (checkfor zero amps). Pull
the governor rod so that the tang on the throttle
lever bears against the idle speed stop screw.
Adjustthe screw to obtain 54-56Hz (44-46 Hz).
(On LPG carburetorsthe stop screwhasa locknut.)
Frequency Adjustments: The frequency specifications for 60 Hz gensets are followed in parentheses by the specifications for 50 Hz gensets.

.

4

ALTITU E
SCALE

A\L)ITUDE
ADJUST KNOB

FIGURES-3.GASOLINE CARBURETOR

F\

1. Set the altitude adjust knob (gasoline only) on
the carburetor to your altitude.
2. Disconnect all loads (check for zero amps).
Then check no-load frequency. If necessary,
turn the governor speed adjusting screw to
obtain a no-load frequency of 62-63 Hz
(51.5-52.5Hz).

FUEL INLET
LIQUID-WITHDRAWAL

I

FUELINLET

I

VAPOR-WITHDRAWAL

I

I

3. Check output voltage. See Generatorif output

voltage cannot be adjustedto within 10 percent
of rated voltage (Table S-1).
4. See Troubeshoofingif the engine runs roughly.

T H R O ~
LNER

STOP SCREW
AND LOCKNUT

FIGURE S-4. LPG CARBURETOR

S-6

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DroopAdjustmenkxThe frequency specifications
for 60 Hz gensets are followed in parentheses by
the specifications for 50 Hz gensets.

and, if necessary, readjust the governor
speed adjusting screw to return to 62-63
Hz (51.5-52.5 Hz) no-load frequency.
Check droop again and repeat the adjustments, if necessary.

1. Connect rated load.
A. Load (watts) is the product of volts (V) and
amps (A).
Load (watts) = V x A

3. Check governor response under 1/4,1/2 and
314 rated loads. See Troubleshootingifhunting
is unacceptable.

Carburetor Replacement

(A 1.O power factor, obtainable with a resistance load bank, is assumed. True
ratedoutput might not be obtained if appliances are used as part of the load.)

Other than turning the altitude adjust knob shown in
Figure S-3, which changes the main fuel mixture
within a limited range (gasoline carburetors only),
fuel mixture adjustments should not be attempted
on gasoline or LPG carburetors. Norshouldthe carburetor be overhauled. Instead, a malfunctioning
carburetor should be replaced. Before replacing a
carburetor, however, make certain 1) that all other
necessary engine and generator adjustments and
repairs have been performedand 2) that the carburetor is actually malfunctioning, by carefully following the troubleshooting procedures in Troubleshooting.

B. See Generator if output voltage cannot be
adjusted to within 10 percent of rated voltage (Table S-1).
TABLE $1. VOLTAGE SPECIFICATION

I

OUTPUT
VOLTAGE

I

NO-LOAD
VOLTAGE

I

120V,lPH
120/240V, 1PH

I

132
264

I

I

FULL-LOAD
VOLTAGE

I

I

112

I

I

224

I

2. Check and adjust droop.

A. If droop (from no-load frequency) is more
than 3 Hz (3.5 Hz) for Model BGE or 4 Hz
(3.5 Hz) for Model NHE, turn the governor
sensitivity adjusting screw (Figure S-2)
one turn counterclockwise. Disconnect
the load and, if necessary, readjust the
governor speed adjusting screw to return
to 62-63 Hz (51.5-52.5 Hz) no-load frequency. Checkdroopagain and repeatthe
adjustments, if necessary.
B. If droop (from no-load frequency) is less
than 2 Hz (2 Hz) for Model BGD or 3 Hz
(2 Hz) for Model NHD, turn the governor
sensitivity adjusting screw (Figure S-2)
one turn clockwise. Disconnect the load

LPG carburetorsare usually not the cause of problems. Make certain all otherpossible causes of the
problem have been eliminatedbefore replacing an
LPG cahuretofi

1-

Unauthorized modifications or replacement of fuel, exhaust, air intake or speed
control system components that affect engine
emissions are prohibited by law in the State of
California.

See the instructionson how to remove and replace
the carburetor underthe subheadings AIR CLEANER ASSEMBLY and CARBURETOR AND INTAKE
MANIFOLD ASSEMBLY in this section.

s-7

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Automatic Choke (Gasoline Sets)

1. Apply a vacuum of at least 100 mm (4 inches)
of mercury to fully pull in the choke breaker
arm.
2. Insert a 8.6 mm (0.337 inch) drill rod between
the choke plate and the carburetor throat.
3. If necessary, bend the link at the point shown
until the lip of the choke plate just touches the
drill rod. Use two pliers to bend the link.

See Figure S-5.The automaticchoke is operatedby
a bi-metalheaterassembly and a vacuum breaker
assembly. Replace faulty choke components and
reassembleas shown. Adjust the choke breakerassembly each time it is assembled to the carburetor,
as follows:

.

FIGURE S-5. CHOKE ASSEMBLY

S-8

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by any means, is strictly prohibited.

2. Push the Start/Stop switch to START and hold
it there for several seconds until the fuel pressure stabilizes. Fuel pressure should stabilize
between 3.5 and 6 psi (24 and 41 kPa).

Fuel Pump (Gasoline Gensets)
The fuel pump delivers fuel to the carburetor at
3.5-5 psi (24-35 kPa) and has a lift capacity (suction) of 3 feet (0.9 meters).

3. Repeat the test with the vehicle engine running.
A fuel pressure greater than 6 psi (41 kPa) is not
acceptable. Findout why the pressureis high. If it is
high when the vehicle engine is not running, check
to see that the proper Onan supplied pump is being
used. If it is highwhen the vehicle engine is running,
a separate fuel pickup tube in the fuel tank, or
equivalent means, will be required.

w
j Do not substitute an automotive
fuel pump for the standard pump removed from
the genset. Other pumps can cause carburetor
flooding because of the highpressures theydevelop. Carburetor flooding can cause poor performance and engine damage and lead to possible fire and severe personal injury or death.
Fuel pressure at the carburetor fitting must not
exceed 6psi (41 kPa) under any operating condition.

If the fuel pressure is less than 3.5 psi (24 kPa),
check for fuel restrictions in the system. The pump
will haveto be relocatedcloserto the fuel tank if it is
locatedmorethan 3feet (0.9 meters) above the end
of the fuel pickuptube in the fuel tank. If the pump is
defective, replace it with the appropriate Onan
pump. The pump is not serviceable.

Fuel Pressure Test:
1. Disconnectthe fuel line at the outlet of the fuel
pump and connect a pressure gauge at the
pump outlet. A gauge calibrated for 0-15 psi
(0-100 kPa) is recommended. Do not tee into
the fuel line. This is a static pressuretest.

See the Installation Manual for important recommendations regardingthe fuel supply system.

s-9

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LPG System-Liquid Withdrawal

handle LPG liquid at the same pressure as in the
LPG container. Depending on ambient temperature, LPG container pressure can exceed 200 psi
(1379 kPa). Therefore, discharge or leakage from
LPG liquid-containingcomponentscan result in the
escape of large volumes of flammable and explosive gas.

See Figure S-6. For liquid withdrawal systems the
LPG container($ must be equipped to withdraw
LPG as a liquid. See the InstallationManualfor important recommendationsregardingthe installation
of a LPG liquid withdrawal type of fuel supply system.

lgWAR”G1 LPG is flammable and explosive
and can cause asphyxiation. NFPA 58, Section
7.6 requires all persons handling LPG to be
trained in proper handling and operating procedures.

TWO-STAGE LPG
PRESSURE REGULATOR

LPG VAPORIZER
COILS

.

Purging fhe LPG System: It is imperativethat the
LPG system be purged before disconnecting fuel
system components.

1-b

Large volumes of LPG can be released in the process of disconnecting a liquidwithdrawal type of LPG supply system. SeeDisconnecting Set from RV Systems (Page S-2)
for the proper procedures and precautions.

It is importantto understandthat the fuel filter, solenoid shutoff valve, vaporizer and demand regulator

EXHAUST MANIFOLD
WITH BAFFLE

*

ONE OF TWO REGULATOR

LPG FUEL SHUTOFF

MOUNTING SCREWS

SOLENOID

LPG FII~NG’AND
HOSE
TO CARBURETOR

1

LPG FIL R AND FUEL
SUPPLY CONNECTION

FIGURE S-6. LPG SYSTEM COMPONENTS FOR LIQUID WITHDRAWAL

s-I 0

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by any means, is strictly prohibited.

Demand Regulafor: See Figure S-7. The twostage demand regulator delivers vaporized LPG to
the carburetor. The primarystage receives LPGvapor (and liquid) at LPG container pressure and reduces it to approximately 1-1/2 psi (10.3 kPa). The
secondarystage is a demandregulatorthat delivers
LPG vapor at the rate demanded by the carburetor.
The regulator should require little attention if the
genset is operated regularly. Most regulator malfunction is due to:
Hardened diaphragms and valve seats. The
pressure regulator in a genset that has been
operated and then stored for a long time might
require replacement because diaphragms,
gaskets and valve seats tend to shrink and
harden over time.
Fuel impurities and oils dissolved in the liquid
LPG. Impurities can form granules that become embedded in the secondary valve seat
causing it to leak andoils can clogpassages inside the regulator. The results could be hard
starting, erratic idling and poor load acceptance.
Tesfingthe Demand Regulator: Use compressed
air and a pressuregauge to test the regulatoras fol-

lows:

.

1. Connect a pressure gauge to the test port on
the back of the regulator.
2. Connect a source of compressed air (at least
80 psi [550 kPa]) to the inlet opening and open
the air pressure valve.
3. If the primaryvalve is sound, the gauge will indicate approximately 1-1/2 psi (10.3 kPa) and
the pressure will remain constant. Fluctuating
pressure indicates a leaking primary valve
seat.
4. Close the air pressure valve and observe the
pressure gauge. The pressure should remain
constant. If the pressure drops, the secondary
valve seat is leaking.
5. Disassembleand cleanthe regulatorassembly
if it does not pass eithertest. Replacethe regulator if it still does not pass either test.

IaWARNINGl

Most parts cleaning solvents
are flammable and corrosive and can cause
severe burns and inflammafion. Use only
as recommended by the manufacturer.

SECONDARY
VALVE

.

PRIMARY
VALVE

PRIMARY
DIAPHRAGM

FIGURE S-7. DEMANDREGULATOR ASSEMBLY
CONNECTM E INLETTO A
SOURCE OF COMPRESSEDAIR

/ -

THE GAUGESHOULD INDICATE
APPROXIMATELY
1-1/2 PSI (10.3 KPA) AND HOLDSTEADY

FIGURE S-8. TESTING THE DEMAND REGULATOR
(LIQUID-WITHDRAWAL SYSTEM)

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Fuel Filter; See Figure S-9. The fuel filter removes
rust and scale and other solid particles from the
LPG liquid to keep them from embedding in the
valve seats of the shutoff valve and pressure regulator and causingthem to leak. A magnettraps iron
and rust particles and a filter element traps nonmagnetic particles.

fold. Exhaust heatvaporizesthe LPGliquid. The vaporizer is not removablefrom the exhaust manifold.

1-b

Bending the fuel Vaporizer tubing
could weaken it to the point that it could crack
allowing fuel under high pressure to escape,
which could result in severe personal injury or
death.

Disassembling and Cleaning the Fuel Filter;

Fuel Shutoff Solenoid Valve: Test the fuel solenoid by disconnecting its long lead and jumpering it
directly to the battery positive (+) terminal on the
genset. Replace the solenoid if it does not "click"
open when it is powered.

1. Purge the LPG system as instructed on Page
S-2 before beginning disassembly.
2. Remove the four capscrews and lock washers
that hold the filter bowl to the filter body.
3. Separate the filter bowl from the filter body and

discard the O-ring seal.
4. Remove the nut and washer from the center
stud and pull out the filter element.
5. Wash the filter element in keroseneto remove
the particles it has collected. Blow it dry with
low pressure (30 psi/207 kPa) compressedair.
Replace the filter element if damaged.
6. Wipe the magnet clean of the particles it has
collected.
7. Installa cleanfilter element usingtwo new gaskets and securely tighten the center stud nut.

GASKET

\

O-RING

8. Place a new O-ring in the filter bowl sealing
groove.
9. Align the reference mark on the filter bowl with
the referencemarkonthe filter body andtorque
the capscrews to 65 Ib-in (7.2 N-m). Check for
and fix leaks at the filter when connections
have beenmadeto the fuel supply system. The
fuel filter operates at fuel supply tank pres-

sure.
Fuel Vaporizer; The fuel vaporizer consists of
several wraps of tubing around the exhaust mani-

r--

(D

FIGURE $9. LPG FUEL FILTER
(LIQUID WITHDRAWALSYSTEM)

.

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LPG System-Vapor Withdrawal

rnand regulator. These are available as a kit for
mounting near the genset. See Figure S-10.

b

See the Installation Manual for important recommendations regardingthe installation of an LPG vapor withdrawal type of fuel supply system. Gensets
equipped for vapor withdrawal of LPG must be
equipped with a fuel shutoff solenoid valve and de-

SOLENOID PIGTAIL

1-1

LPG is flammable and explosive
and can cause asphpiafion. NFPA 58, &don
1.6 requires a// persons handhg LPG to be
~rain~j~~fo~r~
andoperafingprocean~/jng
dum.

GAS SUPPLY HOSETO

MOUNTING

FUEL SHUTOFF

.

\

VENTPRESSURE-BALA~CEHOSE

(Must extend outside the genset compartment to
prevent accumulation of LPG in Compartment in the
event the diaphragm leaks and to prevent erratic fuel
delivery because of pressure fluctuations cause by
the cooling airflow through the compartment.)

DEMAND REGULATOR
(The regulator must be mounted such that the diaphragm is in
vertical plane, as shown, to maintain calibrated gas pressure.

FIGURE S-10. LPG SYSTEM COMPONENTS FOR VAPOR WITHDRAWAL

S-I3

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LPG Supply Pressure: LPG supply pressure must
be maintainedat 9-13inches (229-330mm) water
column (WC) underall conditions. Adjust the supply
pressure as follows:

7. Disconnectany jumpers which may have been
used to energize the fuel solenoid and thread
inandtighten the pressuretest port plugunless
tests are going to be continued.

1. Close the gas shutoff valve(s) at the LPG container(s).
2. Removethe 1/8 inch pipe plugfrom the regulator test port (Figure S-11) and connect a manometer calibratedin inchesor mrnWC (water
column) having a scale range of at least 14 inches (350 mm).
3. Open the LPG container shutoff valve and try
starting the genset.
4. While the genset is running, check the manometer and adjust the LPG supply pressure
regulator to obtain 11 inches (279 mm) WC. (If
there is a secondary pressure regulator in the
supply line, adjust the secondary regulator
insteadof the primaryregulatorat the LPGcontainer.)
5. If the genset will not start, jumper the fuel solenoid to the battery cable connections on the
genset so that it stays open (the regulator will
keep gas from f1owing)and then check and adjust the LPG supply pressure.
6. If the genset is operable, check LPG supply
pressure under full load. If it drops below the
minimum required pressure, either the LPG
container is too small to provide the rate of vaporizationnecessaryor it is less than half full or
the supply line is too restrictive.

Fuel Shutoff Solenoid Valve: Replacethe fuel solenoid if it fails to open (as indicatedby the absence
of gas pressure on the manometer scale inthe previous test) when it is jumpered across the the battery cable connections at the genset.

,

Demand Regulator Lock-Off Pressure Test:
Lock-off pressure is determinedas follows by pressurizing the back (vent) side of the regulator diaphragmto simulate carburetor venturi vacuum:
1. Continue with the test setup for adjusting LPG

supply pressure shown in Figure S-11. If the
regulatoris beingtested on the bench, connect
it to a source of air pressure regulated to 11
inches WC (280 mm WC).

1-b

If this is a bench test of fhe regulator,make sure the diaphragm is in a vertical plane (see Figure S-IO), otherwise the
weight of the diaphragm will cause erroneous readings of lock-off pmsure.

2. 'T' in two hoses to the end of the hose connected to the regulator vent fitting (3/8inch
I. D.). Use one hose to provide the test pressure andthe otherto measurepressure by connecting it to an inclined manometer calibrated
with 0.01 inch or 0.1 mm divisions and having
a range of at least 1 inch (25mm).

.

s-14

Redistribution or publication of this document
by any means, is strictly prohibited.

3. Disconnect the hose to the carburetor and at-

*

inches WC (3.8and 6.4 mm WC).

tach a soap bubble to the regulator outlet hose
fitting. While readingthe pressure indicatedby
the inclinedmanometer and watching the soap
bubble, blow lightly into the hose being usedto
pressurize the regulator. Regulator lock-off
Dressure is the minimum Dressure that will
cause gas to flowthroughthe regulator, as indicated by the expanding soap bubble. (At first
the soap bubble mayexpanddueto diaphragm
movement but will stop expanding if gas or air
is not flowing through the regulator.)
Replace the demand regulator if the lock-off
pressure does not fall between 0.15 and 0.25
LOCK-OFF ADJUSTING SCREW
(Beginning Spec M, this screw is
not accessible for adjustments)

1-

Unauthorizedmodifications or
replacement of fuel, exhaust, air intake or
speed control system components that affectengine emissions are prohibited bylaw
in the State of California.

4. If the genset is mounted in a compartment,
make sure the ventlpressure-balancehose is
routed properlyto the outside.
5. Reconnect the hose to the carburetor, disconnect any jumpers which may have been used
to energize the fuel solenoid and thread in and
tighten the pressure test port plug.

LPG OUTLET TO
CARBURETOR

MANOMETER CONNECTED
TO LPG SUPPLY PRESSURE TEST PORT

LPG INLET
(11 inch WC pressure)

.

-BALANCE HOSE
r a view of the vent

FIGURE S-11. LPG SUPPLY PRESSUREAND REGULATOR LOCK-OFF PRESSURE

s-I5

Redistribution or publication of this document
by any means, is strictly prohibited.

Redistribution or publication of this document
by any means, is strictly prohibited.

Supplement 9651065
Date: 197
Insert with
Title: BGE/NHE Service Manual
Number (Date): 9650528 (994)

PURPOSE

SERVICE MANUAL 965-0528 REVISIONS
1. Insert this Supplement in its entirety under
the front cover of the manual. (Do not discard
Supplement 965-1060.)
2. On Page 2-2 replace Figure 2-1 with Figure S-1
on Page S-2 of this supplement.

This Supplement is used in addition to Supplement
965-1060. It transmits the revisions to the Service
Manual necessary for covering all changes made
since Supplement 965-1060 was issued.

!

!

The engine exhaust from this product
contains chemicals known to the State
of California to cause cancer, birth
defects or other reproductive harm.

S-1

Redistribution or publication of this document
by any means, is strictly prohibited.

BGE/NHE
(Gasoline)

REMOTE START CABLE
CONNECTION

BGE/NHE
(LPG)

REMOTE START CABLE
CONNECTION

FIGURE S-1. TYPICAL EMERALD GENERATOR SETS

S-2

Redistribution or publication of this document
by any means, is strictly prohibited.

3. On Page 7-5 replace Figure 7-3a with Figure
on Page of this supplement.

S-3

Redistribution or publication of this document
by any means, is strictly prohibited.

Supplement 965-1069
Date: 11-98

lnserl withTitle: BGE/NHE Service Manual
Number (Date): 965-0528 (9-94)

PURPOSE
This Supplement transmits the revisions to the Service Manual necessary to cover changes beginning with
Spec N gensets. Gensets beginning with Spec N have a sealed-type remote control connector and single,
16-pin connector on the genset control board.

SERVICE MANUAL 965-0528 REVISIONS
1. Do not discard Supplement 965-1060,

which covers changes beginning with
spec M.
2. Look for statement “BGE Spec F through K,
NHE Spec E through K” on the front cover.
Strike out the “K” in both places and write in “P’
in both places.
3. On Page 6-14, Step 6, change“12.6 and 15.4k
ohms” to “12.6kand 15.4k ohms.”
4. On Page A-1 (Appendix A) write:

“Prior to Spec N: In lieu of testing the connector pins with a meter, use control board tester
No. 420-0572 and the appropriate adapter harness to determine whether a control board
needs to be replaced. Follow Instruction Sheet
G220 packaged with the tester.”

“Beginning Spec N: See Page A-11 .”

5. Insert attached Page A-11 after Appendix A
Page A-1 0.
6. Replace Page B-1 (Appendix B) with the
attached PageB-1 and add the attached
Pages B-8 through B-11.

7. On Page ii (Table of Contents), change the
Heading “Appendix B SPEC J and K DIAGRAMS”, to “Appendix 6. Later Wiring Diagrams”.

8. On Page ii under Appendix B. Later Wiring
Diagrams add the entries:
“Beginning Spec N:
BGENHE, 60 HZ (611-1244).
. .B-8
BGE/NHE, 60 Hz, LP (611-1253)
B-9
BGE/NHE, 50 Hz, LP (611-1254). .
B-10
BGE/NHE, 50 HZ (611-1248). . .
.Ell’’

. . . ..
. . .. .
. ..
.. .

Page 1 of 1 with attachments A-1 1, B-1 and
B-8 through
B-11 of this document
Redistribution
or publication
by any means, is strictly prohibited.

Redistribution or publication of this document
by any means, is strictly prohibited.

CONTROL BOARD TESTING (BEGINNING SPEC N)
If the genset does not crank, or cranks but does not
start, and you think the cause might be a faulty control board, conduct the following tests to make sure.

'

.

make for easier connections at the battery terminals.
Depending on results:

First remove the control panel and disconnect
PIIJI. For easier test connections at P i , it is recommended that you make up a test harness with
Onan 16-Socket Connector 323-1 487-04 and
Sockets 323-1486. Also, use alligator clips on the
ends of the leads attached to pins 2,4,7 and 11 to

Go back to Troubleshoofingif a meter or light
does indicate B+ at each pin in both tests: PC

0

board A I is not faulty.
Replace control PC board A I if a meter or light
does not indicate B+ at each pin in both tests.

0

Tests

Results

B+ (12 VDC) to P1-7 and B- to P1-11
and hold down the control switch in the Start
position.

A meter or light should indicate B+ at:

1. Apply

P1-1 (field flash)
P I 4 (starter)
P1-6 (ignition)
Pl-12 (fuel and choke)

2. Continuing Step1, apply B+ to Pl-2 and B- to

A meter or light should continue to indicate B+ at:
P1-6 (ignition)
P1-12 (fuel and choke)

P1-4,to simulate start disconnect, and then let
go of the Start switch.

...."....

11

2

3

4

5

6

7

81

-

-

-

0 0 0 0 0 0 0 0
11 12 13 14 15 161

r9

.

A-11

Redistribution or publication of this document
by any means, is strictly prohibited.

,

Redistribution or publication of this document
by any means, is strictly prohibited.

Appendix B. Later Wiring Diagrams
WIRING DIAGRAM

V

Beginning Spec J:
.
BGElNHE 60 HZ
BGE/NHE 50 Hz
BGE 60 Hz, 100 V
Beginning Spec K:
BGE/NHE 60 Hz
BGUNHE 50 Hz
BGE 60 Hz, 100 V
Beginning Spec N: (sealed remote connector)
BGUNHE 60 Hz
BGE/NHE 60 Hz, LP
BGElNHE 50 Hz, LP

B-1

DRAWING No.

PAGE No.

611-1206
611-1207
611-1208

B-2
B-3
B-4

611-1220
611-1221
611-1222

B-5
B-6
B-7

611-1244
611-1253
611-1254

B-8
B-9
B-1 0

Redistribution or publication of this document
by any means, is strictly prohibited.

I

VR1

I

I
I
I
L
--

1I

I

NOTES:

1. FOR P Z I J Z :

A

0
C
E
F

--.- sw

QROUND
KMT STOP
RMT START
01

5W 61

VRl
T1

VDLTAGE C E W T O t l
IGN CCiL

53

EN fiW).€
SUKH-LOW OC P E S

52

Redistribution or publication of this document
by any means, is strictly prohibited.

WIRING DIAGRAM

A2

A3

s-

A

S r HFMATIC

'

I
I
I
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I
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L---

4
I
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f

/

I

I

NOTES :

1. FOR P 2 / J Z :

A

E
C

E
F

-

---

OROUNO
RMT STOP
RMT STAR
SW
SW

Bt
Bt

I
I
I

I
I
I
I
I
I

m1

I
L

TI

VaTAQ R E W T O a
IGN CCU

53

IGN W

92
R6

w1ENTmw

r

R5
K5
K1
GI

GEMATOR

4

F1

FUSE-SLOW BLOW 5A

E3.4
E2
CR6

TBI

-

cniz
CL.5
ET1

P2

E

Shmi-LOW al m
s
ti€S!STM(-BATlERY MaRE

OPT IONAL

€11
A3
A2
AI
AI
ITEM

RBAYIp(i M Y
w Y - s r a R T SOLENMO

SPARK PLUGS

FEL FWF OR FUEL SOL
FECTRER-LPG ONLY
CIRCUT BREAKER !At WTPUTl
CAPACITW
BATTERY 1ZV
REMOTE CONTROL-STAMARD
STARIER
MOTOR
REMOTE CONTAOL.OELUXE
CONTROL ASSY-MEL
CONTROL ASSY-BGEL
DESCRFTKN CR M A l W U

BEGllNNlNG SPEC N BOUNHE 60 HZ. LP-611-1253
Redistribution or publication of this document
by any means, is strictly prohibited.

I

r-PI

'

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'

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CEil

I

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T3 L1

TL L3
T2 L3
T3 L2
T4
T I L1

700-IfOV

'''

200-ZLOV

I

I
-n
100-12ov
I I l * 100-120V f
!
CBI

* T3
T2

L3
T& L2
NOTES

I

C82

4

ZOO-2LOV

1

1 IZOV MAX ACROSS CRI COEIhXTIGNS 2.3

I

2. GROUNJEO AC LEAD- FOR ISOLATED NEUTRAL.
REMOVE JUMPER IW21 TB1-L3. LO AND
CONNECT JUMPER TBl-LO. VRI-C5 NEGI-I

II

3

FOR P 2 l J Z

VRl

WLTAGE REGULATOR

TI

IEW COIL

53

IGN NODULE
WTCH-LOV 0. PRE55
RESISTOR-BATTERY CHARS:
PDTENTlSMETER
RELAY-LPG ONLY
RELAY-STCRT S%ENC;D

s:
R6

R§
t:5
t:1
GI

GENERATCR

F1

F U S S L O W BLOW 5A
SPARK FLLGS
FUEL FLIP? OX FUEL SOL
I; ECiI=IER-LPG C: I-'(
ClKUT FREAKEff I 4 C OUTPUT)

E3 4

E2
ZO'I
iC

---

A
QROUND
8
AHT STOP
C
RMT START
E-SWB+
F-SWE+

CRb
Ch12
CL E
Oil

C"FilClT0f

611
A3

r;2
91
AI

,is%!

Redistribution or publication of this document
by any means, is strictly prohibited.

SCHEMATIC

I

4
' II . .

I

I

I

I

I
I
I

CBI

I

I

P1-11

I
L-/

/

\

\

1
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-

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I

Tsl

,

q !
I

TIII

TL L2

A
-

CB2

~-

I

f

200-24OV

100-120v

E

NOTES
1. 12OV MAX ACROSS VRI CONNECTIONS 2,3
i t 2. GROUNDED AC LEAD- FOR ISOLATED NEUTRAL,
REMOVEJUMPER (WZ) TBI-L3. LO AND
CONNECT JUMPER TBI-LO. VRI-C5 NEGM

TI

53
s2
R5
K4
KI
HI
El

IGN CML
IGIlHOWLE
SWITW-LOW a ffiEss

FOTENTWTER
RBAY.CHOKELFUELWW
RMY-START SoLENoiO
CHOKE

E3,b
E2

GEWTffl
FUSE-XIA
FUSE-XIA
SPARK PLffiS
F M W

CBU

CRCW B
Rum (AC 0UIpun

(45
ET1

CAPACITOR
BATTERY 1ZV
STARTER WTOR

F2
F1

E1

A3
A2
AI
AI
IXMP

REHDTE CONIRK-STAMARO

REHDTE CGVRCi-OELUXE

comtxfisy~
CMrmUASSY-BE

OESCWTKU~LUTERN

BEGllNNlNGSPEC N BGHNHE50 HZ411-1248

.

Redistribution or publication of this document
by any means, is strictly prohibited.

.,

..
.

,

I

.... ... - .

,,, I : t !

'

,

Redistribution or publication of this document
by any means, is strictly prohibited.

Supplement 965-1075
Date: 02-01

hserf withTitle: BGE, NHE Service Manual
Number (Date): 965-0528(9-94)

This supplement transmits the following corrections
to the service manual:

1. On Page 6-14 under Direct Testing Coil With
Ohmmeter: step 6, change "12.6 and 15.4 k

ohms" to:
34.0 to 41.6 k ohms at 68°F (20°C)
Refer to the page 6-1 4 of your manual and write
"Referto Supplement"on it.

Redistribution or publication of this document
of 1
by any means, is Page
strictly 1
prohibited.

Redistribution or publication of this document
by any means, is strictly prohibited.

4. Disconnect the condenser and ignition lead wires at
screw A (Figure 6-1 0).

HIGH VOLTAGE

TERMINAL

5. Remove the condenser, mounted outside breaker
points box on engine adapter flange.
6. Remove the breaker points mounting screws (B)
and lift out the point assembly.

c

LOW VOLTAGE

7. Replace the condenser and point assembly and
install in a reverse order of removal.
8. Use an allen head wrench to adjust set screw C to
obtain the gap setting specified in the Specifications
section. Measure the point gap with a flat thickness
gauge (see Figure 6-1 0).

SECONDARY

PRIMARY
WINDING

Make sure feeler gauge is clean and free of any
grease, oil, or dirt.
The timing is adjusted during initial engine assembly and is fixed by the point gap adjustment. No other adjustment or alignment is necessary.

IRON CORE

9. Replace the point box cover and hold-down wire,
spark plugs, and spark plug leads.
10. Connect negative (-) battery cable to negative batter terminal.

ES-1666

FIGURE 6-11. IGNITION COIL
Ignition Coil Quick Test: This test checks the coil with
the rest of the ignition system.

CONDENSER

bWAR”Gl

’

Gasoline vapor is extremely flammable,
and can result in severe personal injury or death if i p
nited. Make certain that no gasoline or other flammable fumes are present. Park the vehicle in a wellventilated area, and leave the generator set wmpartment door open for several minutes before petiorming this test.

1-

Use extreme care when petionning this
test procedure. To avoid shock-, do not hold the plug
without adequate insulation.

IGINITION

LEADWIRE

V
B

1. Make certain that no gasoline fumes or other flammable fumes are present. Park the vehicle in a wellventilated area, and leave the set compartment
door open for several minutes before performing
this test.

ES-1529-1

FIGURE 6-10, BREAKER POINTS

Ignition Coil

2. Remove a spark plug.

The ignitioncoil (Figure 6-11) is a transformer that steps
up the battery voltage to approximately 20,000 volts, to
fire the spark plug.

3. Reconnect the spark plug wire to the spark plug.
4. Ground the spark plug to bare engine metal.

e

KeeD all ignition coil terminals and connections clean and
secure. Check for loose seams, dents, punctures, and
other mechanical damage. If ignition is poor and other
ignition components are not at fault, test the coil as described below. Make certain of coil Dolaritv: the neaative
(-) terminal connects to the breake; pointi;and thipositive (t)terminal connects to a battery positive (t)source
within the control.

5. Crank the engine.
-

A strong spark should appear between the plug center
and the side electrode. A weak spark
that the coil or wiring may be defective.

813

Redistribution or publication of this document
by any means, is strictly prohibited.

Direct Testing Coil Wth Ohmmeter: The coil is re-

Wiring

moved from the circuit to perform this test.

The ignition system wiring includes:

1. Remove all wires attached to the ignition coil.

One positive (B+)wire, which conducts low voltage

2. Remove the coil from the engine.

. from the battery to the primary winding on the coil.

3. Inspect the terminals for corrosion, looseness,
cracks, dents and other damage. Look for carbon
runners around the high voltage terminals. (These
indicate electrical leakage.) Replace a damaged or
leaking coil.

One negative (-) wire, which conducts low voltage
to the points and condenser.
Two wires which carry the high voltage from the secondary coil winding to the spark plugs. The plugs
and coil secondary are grounded to the engine. The
ignition coil primary (low voltage side) is grounded
when the breaker points close.

4. Clean the outside of the coil with a cloth dampened
in parts-cleaning solvent.
5. Measure resistance in the primary circuit: connect
the ohmmeter leads to the positive (+) and negative
(-) terminals on the coil. This resistance should be
between 3.87 and 4.73 ohms. Replace the coil if the
resistance is higher: high resistance indicates an
open circuit or a poor connection inside the coil.

.

Check all low voltage wiring for loose connections and
breaks in the insulation. Clean all terminals and connections, and use an ohmmeter to test them for continuity.
Use a megger (high-range ohmmeter) to check for
breaks in the plug wire insulation.

6. Measure resistance in the secondary circuit; connect the ohmmeter leads to the two high voltage terminals (see Figure 6-12). This resistance should be
between 34.0 and 41.6 k ohms at 68°F (20°C). R e
place the coil if it is not within this specification. Lower resistance indicates a shortened secondary
winding, and higher resistance indicatesthe coil has
excessive internal resistance or an open circuit.

CRANKCASE VENTILATION SYSTEM
The crankcase breather prevents pressure from building
up in the crankcase. It prevents oil contaminationby routing moisture, gasoline vapors, and other harmful blow-by
materials from the crankcase to the carburetor and combustion chamber. A sticky crankcase breather can cause
oil leaks, high oil consumption, rough idle, reduced engine power, and rapid formation of sludge and varnish in
the engine and oil in the breaker point box.
,

The crankcase breather is vented directly below the generator set. For this reason, the generator set should only be
used in environments where oily vapor and dust do not
create a problem.

1-1

Crankcase breather vapor contains
poisonous carbon monoxide which can cause personal injury or death. Do not run the generator set
while parked unless the undercarriage is exposed to
a steady airflow

' 2
E51373

FIGURE 6-12. TESTING COIL SECONDARY
Spark Plugs
Spark plug inspection is described under Electronic Igni-

tion.

6-14

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by any means, is strictly prohibited.

Table of Contents
SECTION TITLE
1

PAGE

SAFETY PRECAUTIONS ..............................
Inside Front Cover
INTRODUCTION ................................................. 1-1
About this Manual ...............................................1-1

..............................................
SPECIFICATIONS ................................................
Model Identification

2
3

4
5

6

7

8

1-1
2-1
DIMENSIONSAND CLEARANCES ..................................
3-1
TORQUE SPECIFICATIONS ........................................ 4-1
PREPARINGTO SERVICE .........................................
5-1
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
Engine Tools ....................................................5-1
Generator and Control Tools .......................................
5-1
Safety Considerations ............................................ 5-1
Set Removal ................................................... 5-2
ENGINE PRIMARY SYSTEMS ..................................... 6-1
Introduction .................................................... 6-1
Troubleshooting ................................................. 6-1
Exhaustsystem ................................................ 6-5
6-8
Cooling System .................................................
Electronic Ignition System (Begin Spec G) ........................... 6-10
Breaker Ignition System {Prior to Spec G) ........................... 6-12
Crankcase Ventilation System .................................... 6-14
Combustion Chamber ........................................... 6-15
Governor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-15
Fuel System - Gasoline .......................................... 6-17
Fuel System - LPG (Liquid Withdrawal) .............................
6-25
Fuel System - LPG (Vapor Withdrawal) ............................. 6-31
6-33
Electric Starter .................................................
CONTROL ...................................................... 7-1
Introduction .................................................... 7-1
Control Description ..............................................7-1
Control Operation ............................................... 7-3
Testing Control Board A I .........................................7-4
Control Troubleshooting ..........................................7-6
GENERATOR .................................................... 8-1
GeneratorEontrol Component Descriptions ........................... 8-1
8-2
Generator Operation .............................................
Generator Troubleshooting ........................................ 8-8
Generator Service .............................................. 8-10
Brushes and Slip Rings .......................................... 8-14
8-15
Testing Voltage Regulator VR1 ....................................
Generator Testing .............................................. 8-15

-

i

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by any means, is strictly prohibited.

Table of Contents (Continued)
~~

~

SECTION TITLE
9

PAGE

.......................................
.......................................................

ENGINE BLOCK ASSEMBLY

9-1
9-1
General
9-1
Oil Filter and Adapter ............................................
CylinderHeads ................................................. 9-1
Valvesystem ..................................................9-2
Gear Cover .................................................... 9-6
GovemorCup ..................................................
9-7
Timing Gears and Camshaft ........................................
9-7
Lubrication System .............................................. 9-8
Piston Assembly ................................................9-9
9-12
Crankshaft ....................................................
Cylinder Block ..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-13
Bearings ..................................................... 9-15
Oil Seals ...... :.............................................. 9-16
10
SERVICE CHECKLIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1
Mounting .....................................................10-1
Lubrication .................................................... 10-1
Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-1
10-1
Initial Start Adjustments ..........................................
Fuel System .................................................. 10-1
Output Check ................................................. 10-1
10-1
Exhaust System ...............................................
Control .......................................................10-1
Mechanical ................................................... 10-1
APPENDIX A TROUBLESHOOTING CHARTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-1
Troubleshooting Electronic Ignition Module . . . . . . . . . . . . . . . . . . . . . . . . . . .A-2
Emerald Control Functions ........................................ A-3
Emerald Control Board Check-Out (300-2784) .........................
A-5
Emerald Control Board Check-Out (300-305613667) .................... A-7
Emerald/Marquis Control Board Check-Out (300-3763-01, 02) . . . . . . . . . . . . A-9
APPENDIX B SPEC J AND K DIAGRAMS
B-1
Spec J BGElNHE 60 Hz (611-1206) ................................. 8-2
Spec J BGElNHE 50 Hz (611-1207) .................................
B-3
Spec J BGE, 60 Hz, 100 V (611-1208) ...............................
8-4
Spec K BGElNHE 60 Hz (611-1220) ................................. B-5
Spec K BGElNHE 50 Hz (611-1221) ................................. B-6
Spec K BGE, 60 Hz, 100 V (611-1222) ...............................
B-7

........................................

ii

Redistribution or publication of this document
by any means, is strictly prohibited.

Section 1 Introduction
ABOUT THIS MANUAL

MODEL I DENTIFlCATlON

This manual providesservice informationfor Onan BGE
and NHE series recreational vehicle generator sets.
This is a complete service manual for the experienced
serviceperson covering troubleshooting, disassembly,
repair, reassembly, and adjustments for the engine,
generator, and control. It is recommendedthat the serviceperson be thoroughly familiar with the principles of
gasoline engine operation and have a basic knowledge
of electrical fundamentals. Other Onan publications
such as ElectricaVMechanicaI Fundamentals (9320408), Onan Generator Training Manual (932-0404),
BGE and NHE Operator’s Manual(965-0128) and Installation Manual (965-0628) are recommended as additional sources of information.

When contacting an Onan Dealer or Distributoralways
supply the complete Model Number and Serial Number
as shown on the set nameplate(Figure 1-1). This information is necessary to identify your set when ordering
replacement parts.
Always use genuine Onan replacement parts obtained
from an authorized Onan Dealer or Distributor. Universal replacementtypeparts (usually intendedfor automotive use) often looksimilar but might not performto Onan
specifications. Only genuine Onan replacement parts
are designed and tested for the application to provide
reliable service and dependable operation.
The model number is made up of code segments that
designate various features or options.

Read all service procedures completely before beginning any repair work and observe all cautions and warnings. It is extremely important that the generator set
installation maintain compliance with the applicable
codes and standards for RV installations (see Installation Manual).The most critical areas of concern include
the exhaust system, fuel system, electrical wiring, compartmentconstruction, and ventilation system. Improper
servicing can create an unsafe installation that can
result in damage to the vehicle and equipment or can
cause severe personal injury or death to the user.

FIGURE 1-1. ONAN NAMEPLATE

Incorrect installation, service, or replacement of parts can result in severe
personal injury or death, and/or equipment damage. Servicepersonnel must be
qualified to perform electrical and mechanical component insfallation.

1-1

Redistribution or publication of this document
by any means, is strictly prohibited.

Section .2. Specifications
Onan opposed 2-cylinder, 4-cycle, air-cooled, gasoline-fueled and propane-fueled models. Front-mounted control
with remote start capability, negative ground, 12-volt, automotive-type starter.

ENGINE DETAILS

.....................
..............................

BGE

............................
.................................................
.............................

NHE

Displacement..
.47.7in? (781.8cm3).
.60.0ins. (983.0cm3)
Compression Ratio. .........................6.9:1
7.0:l
Bore..
.3.25 in. (82.55 mm).
-3.56in. (90.42 mm)
Stroke ...............................2.87in. (72.90mm). .............................
.3.00in. (76.20mm)
Oil Capacity (WIFilter) ............. (Pre-Spec J) BGE: 4.0 Qt. (3.8 L) . . . . . (Pre-Spec J) NHE: 4.0 Qt. (3.8 L)
(Spec J) BGE: 3.5 Qt. (3.3 L) . . . . . . . . . . (Spec J) NHE: 3.5 Qt. (3.3 L)
Ventilation (Free Area).
-85in.* (584.4cm2) ...............................
85 in? (584.4cm2)
Fuel: Gasoline
Lead-Free ..........................................
Lead-Free
Propane .................LPG (Liquid or Vapor Withdrawal). ......... LPG (Liquid or Vapor Withdrawal)
Cylinder Compression
.75-115psi (517-793kPa).
.100-120psi (690-827kPa)
(Hot).

...............
...........................

............................

..................

TUNE-UP SPECS

Spark Plug Gap.. ....................
Point Gap
(Prior to Spec G Only)
Timing
(Breaker Point Ignition)
Timing (Nonadjustable
Electronic Ignition)
Valve Lash: Intake..
Exhaust..

.0.025in. (0.64mm). ..............................0.025 in. (0.64mm)
.0.016 in. (0.41 mm). ........................
NHE: 0.016 in. (0.41mm)

...........................

....................20°BTC.. .......................................... .20°BTC
......................14'-18O BTC ..................................... 14'-18' BTC
..................0.005in. (0.127mm). ............................ .0.005 in. (0.127 mm)
................0.013in. (0.330mm). ............................ .0.013in. (0.330mm)
GENERATOR

Onan-built, four-pole, revolving field, permanently aligned to engine.
NHE

BGE
Frequency
Watts
Volts
Amps
Phase
Wires

50 Hz
3500 (1)
4000(2)
1101220or 1201240
31.8115.9 or 29.2114.6 (1)
36.4118.2 or 33.3116.7 (2)
1
4

60 Hz
4000

5000

120
33.3

120
41.7

1
2

1
4

50 Hz
5000
6300 (propane)
1101220or1201240
45.5122.7 or 41.7120.8
52.5 (propane)
1
4

60 Hz
6500 (gasoline)
120
54.2 (gasoline)
1
4

NHE
BGE
Dimensions"
14.6 in. (371 mm)
Height..
.14.0in. (356mm)
,25.0in. (635mm)
25.3 in. (643mm)
Length,.
21.1 in. (535mm)
Width..
.18.8in. (478mm)
Weight (Approximate, not including exhaust components)
50 and 60 Hr.. ............................... .216 Ib (97.9kg). ........................... 230 Ib (104kg)
BGE & NHE
Fuel Inlet Connection
Gasoline..
114 in. barb fitting
Propane (Liquid Withdrawal)
.1/4in. NPTF
Propane (Vapor Withdrawal)
.3/4in. NPTF
.12volts
Battery Voltage
.360cold cranking amperes
Recommended Battery Capacity (SAE No. 60 360 or equiv. minimum)
.lo0amperes
Cranking Current
r/min at:
60 Hertz
1800
50 Hertz
1500
Output Ratings
Unity Power Factor

....................................
....................................
.....................................

.........................
.........................
.........................

...........................................................................
...............................................................
...............................................................
..................................................................................
................
...........................................................................
.........................................................................................
.........................................................................................
........................................................................

*Under-Floor mount generator set with compartment housing has slightly larger dimensions. Refer to InstallationManual.

2-1

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by any means, is strictly prohibited.

BGE/NHE
(Gasoline)

GOVERNOR
ADJUSTMENTS

SPARK PLUG

/

I\

SPARK
PLUG
\

NOTE: CONFIGURATION AND
PLACEMENT OF FUEL PUMP
MAY VARY DEPENDING ON
GENSET SPEC LEVEL

FUEL FILTER

\
SUMMER1WINTER
ADJUSTMENT
TlON

IBLOWER

tiOUSING

-7ik

/

0

OCFUSE

1
AC CIRCUIT BREAKERS

OIL

REMOTE START
CABLE CONNECTION

/

FILTER

Y
1

,
"

FUELPUMP

FUELPUMP INLET
ADJUSTMENTS

SWlTCH

M.1sm-14

BGE/NHE

HOUSING

REMOTE START
ABLE CONNECTION

FUEL FILTER AND
SOLENOID ASSEMBLY

NEGATIVE (-[BATTERY
CABLE CONNECTION

POSITIVE (+) BATTERY
CABLE CONNECTION

TO PLATE
-. -

LOCATION OPTIONAL

M-1604-9

FIGURE 2-1. TYPICAL EMERALD GENERATOR SETS

2-2

Redistribution or publication of this document
by any means, is strictly prohibited.

Section 3. Dimensions and Clearances
NHE

MODELS

BGE

CYLINDERS AND
PISTON ASSEMBLY

All clearances listed at 70"F (21 C) room temperature.
Values are in inches (millimeters) unless specified
O

otherwise.
Dimensions apply to all BGE/NHE gensets except
as indlcated.
Cylinder Bore
(Std size honed)

3.2490-3.2500
(82.525-82.550mm)

3.5625-3.5635
(90.488-90.513mm)

Cylinder Taper
(Ma)

0.005
(0.13 mm)

0.005
(0.13mm)

Cylinder Out Of
Round (Max)

0.003
(0.076mm)

0.003
(0.076mm)

Clearance In
Cylinder

0.0044-0.0066
(0.112-0.168 mm)

0.0070-0.0090
(0.178-0.229mm)

Ring Gap (top and
second rings)

0.008-0.018
(0.20-0.46mm)

0.009-0.019
(0.23-0.48mm)

Piston Ring #1 (top) Pre-Spec J sets: 0.080-0.081
Groove Width
(2.03-2.06mm)
Spec J sets: 0.0602-0.0612
(1 53-1.55mm)

0.080-0.081
(2.03-2.06mm)
0.0602-0.0612
(1.53-13 5 mm)

Piston Ring #2
Groove Width

Pre-Spec J sets: 0.080-0.081
(2.03-206mm)
Spec J sets: 0.0602-0.061 2
(153-1.55mm)

0.080-0.081
(2.03-2.06mm)
0.0602-0.0612
(1 53-1.55mm)

Piston Ring #3
Groove Width

Pre-Spec J sets: 0.188-0.189

0.1 884.1 89

(4.78-4.80mm)
Spec J sets: 0.1 193-0.1 203
(3.03-3.06mm)

(4.78-4.80mm)
0.1 193-0.1203
(3.03-3.06mm)

Piston Pin
Diameter

0.6875-0.6877
(17.46-17.47 mm)

0.7500-0.7502
(1 9.05-19.06 mm)

Piston Pin Clearance
In Rod

0.0002-0.0007
(0.005-0.01 8 mm)

0.00005-0.00055
(0.001-0.014 mm)

Connecting Rod
Side Clearance

0.0020-0.0320
(0.051-0.813 mm)

0.0020-0.0160
(0.051-0.406mm)

Connecting Rod
Bearing Clearance

0.0020-0.0033
(0.051-0.084 mm)

0.0005-0.0028
(0.013-0.071 mm)

3-1

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by any means, is strictly prohibited.

MODELS

I

BGE

I

NHE

CRANKSHAFT AND
CAMSHAFT
crankshaft Main Bearing
Journal Diameter

1.9992-2.0000
(50.78-50.80
mm)

1.9992-2.0000
(50.78-50.80mm)

Crankshaft Rod Journal
Bearing Diameter

1.6252-1.6260
(41.28-41.30mm)

1.6252-1.6260
(41.28-41.30)

Crankshaft Main
Bearing Diameter

2.001 5-2.0040
(50.84-50.90mm)

2.0015-2.0040
(50.84-50.90mm)

Crankshaft Main
Bearing Clearance

0.0024-0.0042
(0.061-0.107 mm)

0.0024-0.0042
(0.061-0.107 mm)

Crankshaft End
Play

0.006-0.012
(0.152-0.305mm)

0.006-0.012
(0.152-0.305mm)

Camshaft Journal
Diameter

1.3740-1-3745
(34.90-34.91mm)

1.3740-1.3745
(34.90-34.91mm)

Camshaft Bearing
Diameter

1.3757-1.3787
(34.94-35.02
mm)

1.3757-1.3787
(34.94-35.02mm)

Camshaft Bearing
Clearance

0.0015-0.0030
(0.038-0.076mm)

0.0015-0.0030
(0.038-0.076mm)

Camshaft End Play

0.011-0.048
(0.279-1.219mm)

0.0011-0.048
(0.279-1.219 mm)

Valve Spring Free
Length

1.600
(40.64mm)

1.6620
(42.21 mm)

Valve Spring Compressed
Length

1.346
(34.19mm)

1.375
(34.93mm)

Valve Spring Tension
Open

55 Ibs
(25kg)

71 Ibs
(32kg)

Valve Spring Tension
Closed

25 Ibs
(11 kg)

38 Ibs
(17kg)

VALVE AND LIFTERS

3-2

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by any means, is strictly prohibited.

MODELS

BGE

NHE

Valve Face Angle

44O

44O

Valve Seat Angle

45

45O

Valve Stem
Diameter (Intake)

0.2795-0.2800
(7.099-7.112 mm)

0.3425-0.3430
(8.700-8.712 mm)

Valve Stem
Diameter (Exhaust)

0.2780-0.2785
(7.061-7.074mm)

0.3410-0.3420
(8.661-8.687mm)

Valve Guide
Diameter

Intake

Exhaust

Intake and Exhaust

0.2810-0.2820
(7.137-7.163mm)

0.2805-0.2815
(7.125-7.150 mm)

0.3440-0.3460
(8.738-8.788mm)

Valve Stem
Clearance (Intake)

0.0010-0.0025
mm)
(0.025-0.064

0.0010-0.0025
(0.025-0.064mm)

Valve Stem
Clearance (Exhaust)

0.0020-0.0035
(0.051-0.089mm)

0.0025-0.0040
(0.064-0.102mm)

Valve Lifter Diameter

0.7475-0.7480
(18.99-19.00 mm)

0.7475-0.7480
(18.99-19.00 mm)

Valve Lifter Bore
Diameter

0.7500-0.7515
(19.05-19.09 mm)

0.7500-0.7515
(19.05-19.09 mm)

Valve Lifter To
Block Clearance

0.0020-0.0040
(0.051-0.102mm)

0.0020-0.0040
(0.051-0.102 mm)

Valve Seat Outside
Diameter (Intake)

1.4700-1.4710
(37.34-37.36mm)

1.5690-1.5700
(39.85-39.88mm)

Valve Seat Outside
Diameter (Exhaust)

1.1 92-1.193
(30.28-30.30mm)

1.2550-1.2560
(31.88-31.90mm)

Valve Seat Bore
Diameter (Intake)

1.4395-1.4405
(36.56-36.59mm)

1.5645-1S655
(39.74-39.76mm)

Valve Seat Bore
Diameter (Exhaust)

1.1 89-1.190
(30.20-30.23mm)

1.2510-1.2520
(31.78-31.80mm)

~

I

I

I

3-3

I

Redistribution or publication of this document
by any means, is strictly prohibited.

Redistribution or publication of this document
by any means, is strictly prohibited.

Section 4. Torque Specifications

I

MODELS

Use engine oil as a lubricant for all threads
EXCEPT the spark plug and rotor through-bolt threads.
FOOT-POUNDS
(NEWTON-METRES)

TORQUE
SPECIFICATIONS
Cylinder Head (Cold)

BGE

I

16-18

(22-24)

Connecting Rod

12-14

(16-19)

Rear Bearing Plate

25-27

(34-37)

50-55

(68-75)

Oil Base

18-23

(24-31)

Gearcase Cover

8-10

(11-14)

Spark Plug

7-9

(9-12)

Exhaust Manifold

9-11

(12-15)

Intake Manifold

14-16

(19-22)

Rotor Through-Bolt

45-55

(61-75)

Starter Mounting Screws

30-33

(41-45)

Stator Clamp Screws

10-12

(11-16)

Adapter to Engine
Mounting Screws

25-27

(34-37)

25

(34)

30-33

(41-45)

10-12

(11-1 6)

19-22

(26-30)

28-32

(38-43)

Flywheel Mounting Screw

I

_______

Adapter to Generator
Mounting Screws
Rear Vibration Isolator
-Center Screw
-Flange to Drip
Tray Screws
Front Vibration Isolator
-Flange to Oil
Base Screws
-Center Screw

4-1

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by any means, is strictly prohibited.

I

MODELS

NHE

Use engine oil as a lubricant for all threads
EXCEPT the spark plug and rotor through-bolt threads
FOOT-POUNDS
(NEWTON-METRES)

TORQUE
SPECIFICATIONS

18-20- Stud Nuts
15-17 - Capscrews

(24-27)- Stud Nuts
(21-23)- Capscrews

Connecting Rod

27-29

(37-39)

Rear Bearing Plate

25-28

(34-38)

Flywheel Mounting Screw

50-55

(68-75)

OilBase

18-23

(24-31)

Gearcase Cover

8-10

(11-14)

Spark Plug

7-9

(9-12)

20-23

(27-31)

20-23

(27-31)

18-23

(24-31)

7-9

(1 0-12)

Rotor Through-Bolt

45-55

(61-75)

Starter Mounting Screws

30-33

(4i-45)

Stator clamp screws

10-12

(1 1 -1 6)

Adapter to Engine
Mounting Screws

25-27

(34-37)

Adapter to Generator
Mounting Screws

25

(34)

Rear Vibration Isolator
-Center Screw

30-33

(41-45)

10-12

(1 1 -1 6)

19-22

(26-30)

28-32

(38-43)

Cylinder Head (Cold)

I
I
1
I
I

Exhaust Manifold

I

Intake Manifold

I
I

I

Other 318 Cylinder Block
Nuts

-Flange to Drip
Tray Screws
Front Vibration Isolator
-Flange to Oil
Base Screws

I

-Center Screw

I

4-2

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by any means, is strictly prohibited.

Section 5. Preparing to Service
GENERATOR AND CONTROL TOOLS

TROUBLESHOOTING
c

Most service procedures require that the genset be
removed from the vehicle. Because genset installations
vary, removal procedures vary. If removal is a problem,
contact the vehicle manufactureror genset installer for
assistance. Many procedures require that the outer
sheet metal cover assemblies of the generator set be
removed. This section covers this procedure.

Lead or dead-blow hammer
Battery hydrometer
VOM multi-tester
Frequency meter
Armature growler
Load test panel
Jumper wires

The main service areas are covered in these manual
sections:

Many of these tools are available through the Onan tool
catalog (publication #900-0019).

0
0
0

Section 6 - Engine - Primary Systems
Section 7 - Control System
Section 8 - Generator
Section 9 - Engine Block Assembly

SAFETY CONSIDERATIONS
Be totally aware of generator set hazards. Study the
safety precautions on the insidefront cover of this manual, and know the hazards listed in Table 5-1. Approach
the job in a safety conscious manner,to avoid injury and
death.

Troubleshooting charts in each section providefixesfor
common malfunctions.

Safeguards to Avoid Hazards

ENGINE TOOLS
Torque wrench (0-175 ft-lbs 0-240 Nom)
Feeler gauge
Pressure gauge
Spark plug gap gauge
Cylinder compression tester
Carburetor adjustment wrench
Points adjustment tool
Flywheel puller
Snap ring pliers
Gear puller with puller ring
Cylinder ridge reamer
Combination main and cam bearing remover
Combination main and cam bearing driver
Oil seal loader and driver
Piston ring compressor
Piston ring spreader
Cylinder hone
Valve seat cutter
Valve spring compressor
Valve lock replacer
Valve seat driver
Valve guide driver
Slide hammer
Piston groove cleaner
Outside micrometer set (0 to 4 in.)
Telescoping gauge set (1/2in. to 6 in.)
Hole gauge (0.300 in. to 0.400 in.)
Plasti-Gage bearing clearance guide
Standard Torx screwdriver

0

Use personal protection: Wear protective safety
equipment, such as:
-Safety shoes
-Gloves
-Safety glasses
-Hard hats
-Ear plugs

Do not wear rings, jewelry, o'r loose clothing: these
might get caught on equipment or conduct electricity.
0

Develop safe work habits: Unsafe practices cause
accidents. Be familiar with your tools and machines,
to use them safely. Usethe right tool for the job, and
check its condition before starting. Follow all warnings in this manual, and take extra precautions
when working around electrical equipment. Avoid
working alone, and take no risks.

~

M

4

Reduce the hazard: A safe, orderly work area and
well-maintained equipment reduce hazard. Leave
all guards and shields in place on machinery, and
maintain equipment in top condition. Store flammable liquids in approved containers, away from fire,
flame, spark, pilot light, arc-producing equipment
and other ignition sources. Keep the work area
clean, well-lighted, and well-ventilated. Keep fire
extinguishers and safety equipment nearby, and be
prepared for an emergency.

:r

0

5-1

Be prepared for a potential accident: The Red
Cross and public safety departments offer courses
in first aid, CPR, and fire control. Use this information to be ready for an accident. Be safetyconscious, and make safety procedures part of the
work routine.
Redistribution or publication of this document
by any means, is strictly prohibited.

TABLE 5-1
HAZARDS AND THEIR SOURCE

0

0

Fire and explosions
-Leaking fuel
-Hydrogen gas from charging battery
-Oily rags improperly stored
-Flammable liquids improperly stored
-Any fire, flame, spark, pilot light
arc-producing equipment or other ignition
sources

0

ElectricalShock (AC)
-Improper generator set load connections
-Faulty RV wiring
-Faulty electrical appliance
-Faulty generator set wiring

0

Rotating Machinery
-Flywheel fan guard not in place

Burns

0

Slippery Surfaces
-Leaking or spilled oil

0

Heavy Objects
-Removing generator set from RV
-Removing heavy components

-Hot exhaust pipes

-

-Hot engine and generator surfaces
-Hot engine oil
-Electrical short in DC wiring system
-Hot engine coolant

0

Poisonous Gases
-Carbon monoxide from faulty exhaust
-LP gas leaking into coach interior
-Operating generator set where
exhaust gases can accumulate

Stateand federalagencieshave defermined fhaf asbestos, used engineoil,
and benezene cause cancer or reproductive toxicity.
When adding, changing or working with iuel, oil, or
asbestos gaskets fake care not to breathe, ingest or
come into excessive contact with these substances.
Wash hands after use. Wear profective clothing and
equipment. Provide adequate venfilaiion.

SET REMOVAL
Some service procedureswill require that the generator
set be removed from the coach. While there are many
variations, generator set installations are generally
classified as either conventional compartment mount or
below-the-floor mount. In a compartment mount installation, a special compartment (see Figure 5-1) is built
into the coach to house the generator set. The compartment is constructed with a vapor tight barrier that
seals off the generator set from the coach interior. The
generator set is usually fastened to the floor of the compartment, which must be able to support the weight of
the set. Access to the compartment is through a door
located in the exterior of the coach.
In a below-the-floor mount installation (see Figure 5-2),
a special housing is used to suspend the generator set
from the underside of the coach. The housing bolts to
special support members that are built into the coach
framework.The housing is mounted near the exterior of
the coach and limited access is provided through adoor
panel located in the exterior of the coach.

Because of the wide variety of generator set installations, it is not possible to specify the exact removal
procedures for each generator set. If, after examining
the installation, a satisfactory method for removing the
set cannot be determined, contact the RV coach manufacturer to obtain their recommendations before
attempting to remove the set from the coach.
The generator set is heavy and can
ldropped
ZEi@
%l
result in severe personal injury if
during removal. Use adequate lifting devices

to provide sufficienf support for fhe set. Keep hands
and feet clear while lifting.
Special fuel handling procedures are required when
removing an LP gas (propane) powered set. The iuel
system must be purged of LP gas before the set can be
safely removed from the coach. Follow the purging
procedure before attempting to remove an LP gas
powered set. If the generator set is powered by gasoline,
p r o c e e d t o t h e a p p r o p r i a t e set r e m o v a l
section.
LP-Gas (Propane) is extremely
1 - 1result in severepersonalinjury
flammable and poisonous, and can
or deafh if accidentally
ignited or inhaled. Eliminate all possible sources of
cigarettes, and arc-producing machinery or switches
before purging LP-gas from the fuel system. Provide
adequafe ventilation to dissipate LP-gas as it is
released. (Propane gas will sink to the ground and is
not easily detected.)

5-2

n

.

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by any means, is strictly prohibited.

BARRIER

FIGURE 5-1. TYPICALCOMPARTMENTMOUNT INSTALLATION

REAR

PANEL
ASSEMBLY

ws-1122-2

FIGURE 5-2. TYPICAL UNDER-THE-FLOOR INSTALLATION

5-3

Redistribution or publication of this document
by any means, is strictly prohibited.

LP-Gas (Propane) Purging Procedure
To purge the LP-gas from the set fuel system, close the
shutoff valve atthe fuel tankand then startthegenerator
set. Allow the generator set to operate until it runs out of
fuel. Crank the set a few times after it stops to make sure
the fuel system is completely purged of all LP-gas fuel.
If the generator set cannot be operated, move the RV
coach to an outdoor location that is well-ventilated and
is away from open flame, sparks, pilot lights, cigarettes,
and arc-producing machinery or switches. Disconnect
both the vehicle negative (-) battery cable and the
generator set negative (-) battery cable from their
respective battery terminals. Close the fuel shutoff
valves at the fuel tank for both the generator set fuel
supply system and the appliance (stove, heater, etc.)fuel
supply system. In addition, close the fuel shutoff valves
at each appliance.
LP-Gas (Propane) is extremely
k@@%l
flammable and poisonous, and can
result in severe personal injury or death if accidentally

Loosen the conduit connector and pull the load
wires and flexible conduit free of the junction box.
Disconnect the muffler from the exhaust manifold at
the flange connection and disconnect any support
brackets or hangers that connect the muffler to the
set.
On gasoline fueled sets, turn off the fuel shutoff
valve in the compartment and disconnect the fuel
line at the fuel pump. Securely plug the end of the
fuel line to prevent fuel leakage or an accumulation
of explosive gasoline vapor.

*

Gasoline vapor is extremely flam@
!
!
%
!
%
mable
I and can result in severe
personal injury or death iiignited. Make certain all
fuel line openings are plugged to prevent gasoline
vapor from accumulating.

On LP gas (propane)fueled sets, disconnectthe fuel
line (after purging) at the solenoidvalve and plug the
end of the fuel line to prevent entrance of dirt.

ignited or inhaled. Eliminate all possible sources of
ignition such as open flame, sparks, pilot lights,
cigarettes, and arc-producing machinery or switches
before purging LP-gas from the fuel system. Provide
adequate ventilation to dissipate LP-gas as it is
released. (Propane gas will sink to the ground and is
not easily detected.)

Removing Conventional Compartment Mounted
Set From RV
When the generatorset has been disconnected from the
electrical, exhaust, and fuel systems, examine the set
mountingand support system. Locateall mountingbolts
and support members for the set. In most installations,
the generator set drip tray will be bolted to the coach
framework. Depending on the installation, the set may
be removable from the side, back, or bottom.

Slightly open the fuel line (flexible section) at the solenoid valve just enough to allow the LP-gas to slowly
escape. Don’t open the fitting too much or a largequantity of gas will be released.

Verify that the generator set is adequately supported
before loosening any of the mounting bolts or support
members. The most satisfactory way to lift or move the
generator set is to use a forklift truck.

Disconnect the fuel supply hose from the carburetor
and hold it clear of the set. Press in and hold the primer
button on the regulator to release LP gas from the set
fuel system. When no more gas can be heard escaping
from the open end of the fuel supply hose, reconnectthe
hose to the carburetor and proceed to the appropriate
set removal section.

The generator sef is heavy and can
l2EEEl
result in severe personal injury if
dropped during removal. Use the recommended removal techniques and keep hands and feet clear while
removing mounting bolts.

DisconnectingSet from RV Systems

Removing Underfloor Mounted Set From RV

Disconnect the following items from the generator set.

When the generatorset has been disconnected from the
electrical, exhaust, and fuel systems, the set may be
partially removed for limited service or completely
removed from the RV for major service. The generator
set is mounted on a support tray which serves as the
bottom of the underfloor housing. The inner edge of the
support tray is hinged to the rear panel assembly. The
outer edge of the support tray is bolted to a support
bracket (NHE and NHEL models have two support
brackets). A front and rear panel assembly serve as
sides to complete the housing.

1. Disconnect the vehicle negative (-) battery cable at
the battery terminal.
2. Disconnect the generator set negative (-) battery
cable at the battery terminal.
3. Disconnect the generator set positive (+) battery
cable from the start solenoid.
4. Disconnect the remote control wire plug from the
generator set control.
5. Disconnectthegenerator load wiresat the RVelectrical system junction box. Tag the RV circuit wires if
necessaryfor positive identificationwhen reconnecting.

5-4

Y

f

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by any means, is strictly prohibited.

The generator set is completely suspended underneath
the RV coach by the housing assembly. To avoid dropping the set during removal, follow the recommended
set removal procedures.

Partialset RemovakParkthe recreationalvehicle on as
level a surface as possible (surface must support floor
jack wheels.) Then follow these instructions very
carefully.

The generator set is heavy and can
result in sewere personal injury if
dropped during removal. Usethe recommended removal techniques and keep hands and feet clear while
removing mounting bolts.

Fuel, exhaust, electrical, and control connections must
be disconnected as described previously.
1. Park the vehicle on a level surface that can support
the floor jack wheels. Put the transmission in its
PARK position, lock the brakes and remove the
ignition key. Make sure no one moves the vehicle
while performing this procedure.

If generator set will be lefl in the down (lilted) positionfor more than
30 minutes, first drain the oil.

Oilin the engine cylinders can cause
engine damage during starting
attempts. Oil can enter the engine cylinders when the
generator set is in the lowered (tilted)position. Do not
leave thegenerator set in this position formore than 30
minutes H the oil has not been drained.

Dropping the generator set can
l3death.
!E@El
result in severe personal injury
Make sure no one moves the vehicle

or
during this procedure and that the procedure is
performed very carefully and only as instructed.

2. Position a floor jack under the reinforcement ribs of
the drip tray, as shown in Figure 5-3.
3. Raise the floor jack until it just makes contact with
the drip tray, then put a little upward pressure under
the drip tray.

DRIP TRAY

SOLTS(4)

PLACE FLOOR JACK
UNDER DRIP TRAY
REINFORCEMENT RIBS

M-1600-3

FIGURE 5-3. PARTIAL SET REMOVAL

5-5

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by any means, is strictly prohibited.

4. Removethe bolts that secure the side supportto the
drip tray and the underfloor bracket. (Also remove
bolts from the rear support bracket, if removing an
NHE set).
5. Lift the generator slightly until the safety catch on
the side support is clear of the tray. Pull the support
forward and upward until disengaged from the tray
and underfloor bracket.
6. Remove the side support, to provide the clearance
needed for lowering the set.
7. Remove the safety catch from the center of each
hinge assembly, then remove the U-shaped hinge
pin.
8. Slowly lower the generator set until it is clear of all
obstructions, and can be removed from under the
vehicle.

4. Remove the four bolts from the front support
brackets (and the rear brackets, NHE only) and
remove the brackets. This may require slight
adjustment of the floor jack.
5. When the support bracket is removed, the floor jack
will support all its weight on that side. Slowly lower
the jack, being careful to allow the jack to roll as the
generator set swings downward.
6. Supportthe drip tray assembly with wood blocks, so
the floor jack can be removed. This will allow more
access for the service procedure.
Make sure generator is resting
securely before removing floor
jack. Otherwise, fhe generator set can swing
downward causing severe personal injury.

*

Complete Set Removal
Fuel, exhaust, electrical, and control connections must
be disconnected as described previously.
1. Park the vehicle on a level surfacethat is capable of
supporting the floor jack wheels. Put the transmission in its PARK position, lock the brakes and
remove the ignition key. Make sure no one moves
the vehicle while performing this procedure.

1-

Dropping the generator set can
cause severe personal injury or
deaih. Make sure no one moves the vehicle during
this procedure and that the procedure is performed
very carefully and only as instructed.

2. Use a forklift to support the generator set tray at the
points shown in Figure 5-4. Place a wooden block
on one fork so the set will remain level.
3. Raisethe forklift so it contactsthe drip tray; then put
slight upward pressure on the tray. Make certain
that the generator set is supported by the forks
before continuing.

FORK LIFT'

/\' '
M-1601-2

FIGURE 5-4. COMPLETE SET REMOVAL

.

5-6

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-

Section 6. Engine Primary Systems
INTRODUCTION

TROUBLESHOOTING
The engine primary systems can often be servicedwithout removing the generator set from the recreational
vehicle and without major disassembly of the set. Use
the following troubleshooting guide to help locate problems related to the engine primary systems. Refer to
Troubleshooting Generator Set Control in Section 7 for
problems related to starting the generator set.

The engine primary systems include the following:

0

0
0

Exhaust system
Cooling system
Ignition system
Crankcase ventilation system
Governor
Fuel system - gasoline
Fuel system - LPG liquid withdrawal
Fuel system - LPG vapor withdrawal
Electric starter

Beforeconsidering major inspection of the engine due to abnormal
engine performance (engine knocks, power loss, etc.), reler to the
unit Operator’s Manual, Periodic Maintenance Schedule, and perform Cleaning ihe Carburetorand Combustion Chamber with Onan
“4C?

TROUBLESHOOTING ENGINE PRIMARY SYSTEMS

7
1
Many troubleshootingprocedures present hazards which can result in severe personal injury
or death. Only qualified service personnel with knowledge of fuels, elecfricify, and machinery
hazards should perform service procedures. Review safety precautions on inside cover page.

Trouble
Engine
Misfires

Corrective Action

Possible Cause
1. Faulty ignition due to:
a. worn or fouled spark plugs.
**b. worn breaker points.
**c. incorrect ignition timing.
d. faulty ignition coil.
e. faulty plug wires.

**f. faulty point condenser
***g. faulty ignition module

la.
b.
c.
d.
e.

Replace spark plugs.
Replace breaker points.
Set breaker point gap.
Test coil and replace if necessary.
Test spark plug wires and
replace if faulty.
f. Replace condenser
g. Refer to Testing Ignition Module.

2. Lean fuel mixture due to:
a. incorrectly adjusted
fuel mixture screws.
*b. incorrect float level.
c. dirt in carburetor.
d. vacuum leak.

2a. Adjust carburetor main
and idle adjustment screws.
b. Adjust carburetor float level.
c. Disassemble carburetor
and clean all internal passages.
d. Locate leak and correct as required.

3. *Contaminated fuel.

3. Drain fuel tank and refill

4. *Carburetor icing.

with fresh fuel.
4. In cold weather, place air
preheater in winter position.

*Gasoline sets only.
**Prior to spec G only.
***Spec G.
Engine
Backfires

1. Faulty ignition due to:
**a. incorrect ignition timing.
b. incorrect spark plug gap.
**c. faulty point condenser.
2. Lean fuel mixture due to:
a. incorrectly adjusted
fuel mixture screws.
*b. incorrect float level.
c. dirt in carburetor.
3. Mechanical damage to engine.

*Gasoline sets only.
**Prior to spec G only.

6-1

1a.
b.
c.
2a.

Adjust breaker point gap.
Reset spark plug gap.
Replace condenser.
Adjust carburetor main and
idle adjustment screws.
b. Adjust carburetor float
level.
c. Disassemblecarburetor and
clean all internal passages.

3. See Engine Block Assembly
section.
Redistribution or publication of this document
by any means, is strictly prohibited.

TROUBLESHOOTING ENGINE PRIMARY SYSTEMS (Continued)

I-[

Many troubleshootingprocedures present hazards which can result in severe personal injury
or death. Only qualified service personnel with knowledge of fuels, electricity, and machinery
hazards should perform service procedures. Review safety precautions on inside cover page
Trouble

Possible Cause

Corrective Action

~~

Engine
Lacks Power

1. Faulty ignition due to:
**a. incorrect ignition timing.
b. incorrect spark plug gap.

la. Adjust breaker point gap.
b. Reset spark plug gap.

2. Dirty air cleaner.

2. Replace air cleaner.

3. Restricted fuel flow due to:
a. plugged fuel filter or
b. faulty fuel pump.

3a. Clean fuel filter.
b. Test fuel pump and repair or
replace if faulty.

4. Incorrect fuel mixture due to:
a. incorrectly adjusted
fuel mixture screws.
*b. incorrect float level.
c. dirt in carburetor.

4a. Adjust carburetor main
and idle adjustment screws.
b. Adjust carburetor float
level.
c. Disassemble carburetor and
clean all internal passages.
d. Repair vacuum leak.

d. vacuum leak.
5. Exhaust system blocked or
restricted.

5. Locate and remove cause
of blockage.

6. Incorrect valve tappet
clearance.

6. Adjust valve tappets (see
Engine Block Assembly section).

7. Excessive engine wear or
damage to engine.

7. See Engine Block
Assembly section.

8. Carburetor air preheater
set incorrectly.

8. In hot weather,, place
air preheater in summer position.

9. Excessive carbon build-up.

9. Clean combustion chamber.

0. No-load speed set
too low.

10. Adjust governor.

*Gasoline sets only.
**Prior to spec G only.
Engine
Overheats

1. Restricted airflow due to
dirt or debris blocking air
inlet or outlet

1. Clear away any debris that

2. Dirt or oil covering engine

2. Clean away all dirt and oil
from engine cooling fins.

cooling fins.

may restrict airflow to set.
Do not use compartment for
storage area.

3. **Incorrect ignition timing

3. Adjust breaker point gap.

4. Lean fuel mixture due to:
a. incorrectly adjusted
fuel mixture screws.
*b. incorrect float level.
c. dirt in carburetor.

4a. Adjust carburetor main and
idle adjustment screws.
b. Adjust carburetor float
level.
c. Disassemble carburetor and
clean all internal passages.

*Gasoline sets only.
**Prior to spec G only.
Redistribution or publication of this document
by any means, is strictly prohibited.

TROUBLESHOOTING ENGINE PRIMARY SYSTEMS (Continued)

Many troubleshooting procedures present hazards which can result in severe personal injury or
death. Only qualifiedservice personnel with knowledge of fuels, electricity, andmachineryhazards
should perform service procedures. Review safety precautions on inside cover page.

*

Trouble

Black Exhaust
Smoke

White or Blue
Exhaust Smoke

Corrective Action

Possible cause
1. Rich fuel mixture due to:
a. dirty air cleaner.
*b. choke sticking.
c. incorrectly adjusted fuel mixture
screws.
d. dirt in carburetor.

“GasolineSets Only.
1. Lean fuel mixture due to:
*a. incorrect float level.
b. incorrectly adjusted
fuel mixture screws.
c. dirt in carburetor.
d. vacuum leak.

la. Adjust carburetor float level.
b. Adjust carburetor idle and main
adjustment screws.
c. Dissemble carburetor and clean
all internal passages.
d. Repair vacuum leak.
2. Drain and replace fuel.
3. See Engine Block Assembly section.

2. Contaminated fuel.
3. Excessive engine wear.

Engine
Hunts or Surges

la. Replace air cleaner.
b. Clean choke and choke
linkage.
c. Adjust carburetor idle and
main adjustment screws.
d. Disassemble carburetor and
clean all internal passages.

rGasolineSets Only.
1. Sticking or binding
governor linkage.

1. Clean governor linkage.

2. Incorrect governor adjustment.
3. Faulty governor spring.

Check that linkage does
does not touch other parts.
2. Adjust governor speed and
sensitivity.
3. Replace governor spring.

4. Incorrect fuel mixture due to:
a. incorrectly adjusted
fuel mixture screws.
*b. incorrect float level.
c. dirt in carburetor.

4a. Adjust carburetor main and
idle adjustment screws.
b. Adjust carburetor float
level.
c. Disassemble carburetor and
clean all internal passages.

5. Governor mechanism worn
excessively.

5. See Engine Block
Assembly section.

6. Fuel supply problem caused b y
a. faulty fuel pump.
b. contaminated fuel supply.
c. vapor locking.
d. plugged fuel filter.

6. Check fuel pump and replace
if defective.
b. Drain and refill fuel supply.
c. Check for cause of overheating.
d. Replace fuel filter.

7. Carburetor icing.

7. In cold weather, place air
preheater in winter position.

‘Gasoline Sets Only.

6-3

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by any means, is strictly prohibited.

TROUBLESHOOTING ENGINE PRIMARY SYSTEMS (Continued)
Many troubleshootingprocedures present hazards which can result in severe personal injury or
death. Only qualifiedservice personnel with knowledge of fuels, electricity, andmachineryhazards
should perform service procedures. Review safety precautions on inside cover page.

Corrective Action

Possible cause

Trouble
High Oil
Consumption

1. Oil viscosity too light or
oil is diluted.

1. Drain oil and refill with
correct viscosity oil.

(Note: New
engines
sometimes
have high oil
consumption
during break-in)

2. Crankcase breather valve is
dirty or defective.

2. Clean crankcase breather
and replace if defective.

3. Oil leaks.

3. Locate source of leak and

Low Oil
Pressure

8

repair as required.
4. Excessive engine wear.

4. See Engine Block
Assembly section.

5. Light loading.
1. Oil viscosity too light or
oil is diluted.

5. Don’t run set at no-load
for long periods of time.
1. Drain oil and refill with
correct viscosity oil.

2. Low oil level.

2. Add oil as required.

3. Low oil pressure switch

3. Replace oil pressure switch
(see Engine Block Assembly
section).

defective.
4. Faulty oil bypass valve.

4. Inspect oil bypass valve and
clean or replace as required
(see Engine Block Assembly
section.)

5. Excessive engine wear or
defective oil pump.

5. See Engine Block Assembly
section.

6-4

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EXHAUST SYSTEM

Conventional Compartment Mount Exhaust
System
A conventional compartment mount exhaust system

The condition of the exhaust system is extremely critical
on RV generator sets because of the possibility of
exhaust gases entering the coach.

*

w

consists of the exhaust manifold, flange connector,
muffler, muffler strap, hanger, clamps, and tailpipe.
When service is required, disassembleand reassemble
as specified in the following steps.

The exhaust system must be serviced immediately if inspection
reveals leakingjoints or connections, loose fasteners, or broken or
damaged components. The exhaust system must terminate beyond
the perimeter of the vehicle.

Disassembly Procedure

Always replace worn components with new original
equipment replacementparts. Do not attempt to repair a
broken exhaust pipe or manifold by welding and do not
replace worn components with parts that do not meet
factory specifications. Contact an Onan distributor for
proper exhaust kit parts and installation instructions.

1. Loosen the front muffler clamp, muffler strap, and

tailpipe hanger. Remove the muffler and tailpipe
assembly (see Figure 6-1).
2. Remove the screws that secure the exhaust tube to
the exhaust manifold. Removethe exhaust tube and
exhaust gasket.

Inhaling exhaust gases can cause
lAWAR"Gl
severe personal injury or death.
Modifying the exhaust system may allow poisonous

Completionof the remaining steps requiresthat the generator
set be removed from the vehicle. Refer to Preparing to Service
(Section 5) for the set removal procedures. For LPG sets, also
perform the procedure for purging LPG from the fuel line.

exhaust gases to enter the vehicle. Use only Onan
replacement parts to service the exhaust system.
Unauthorized modifications will void the Onan warranty. Liability for injury or damages due to unauthorized modifications becomes the responsibility of the
person making the change.

3. Remove the cooling system noise shield and scroll

(see Cooling in this section) to provideaccess to the
exhaust manifold.
4. Remove the screw that secures the exhaust manifold outlet flange to the exhaust manifold support
bracket.
5. Removethe four exhaust manifold screws and liftoff
the exhaust manifold and the two manifold gaskets.

Two basic exhaust systems are used with Emerald series generator sets. Figure 6-1 shows a typical exhaust
system for a compartment mount generator set. Figure
6-2 shows a typical exhaust system for un underfloor
mount generator set. Separate sections cover the service procedures for each exhaust system. Also refer to
specific kit installation instructions.

MUFFLER STRAP
CUTOUT

L BRACKET

sc
FRONT SET VIEW

MP (MARKED 1-1/2)

LOCK WASHER

SCREW

-

MS-1147-3

MUFFLER INLET

FIGURE 6-1. CONVENTIONAL COMPARTMENT MOUNT EXHAUST SYSTEM

6-5

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by any means, is strictly prohibited.

Assembly Procedure:

10. Clean the spark arrester muffler every 100 hours of
operation. Remove the 1/8-inch pipe plug in the
bottom of the mufflerand run the set forfive minutes.
Then replace the pipe plug. Inspect the exhaust
system for leaks at least every eight hours of running time.

Inhalation of exhaust gas can result
in severe personal injury or death. To
prevent exhaust leaks, install all gaskets, clamps,
straps, and hardware as specified. See Tailpipe
Recommendations in this section.

Underfloor Mount Exhaust System

1. Install the exhaust manifold using new gaskets.
Tighten the four manifold screws to the specified
torque.
2. Install the 5/16-18 screw, lock washers, and nut
that secure the manifold outlet flange to the manifold support bracket and tighten securely.
3. Install the cooling system scroll and noise shield
(see Cooling System in this section).

*

An underfloor mount exhaust system consists of the
exhaust manifold, muffler; clamps, hanger (if required),
and tailpipe. When service is required, disassemble and
reassemble as specified in the following steps.

Disassembly Procedure
Contact with hot engine parts can
cause personal injury. The genset
should be shut down and allowed lo cool before performing this procedure.

If no other service is required, install the generator set in the
vehicle before completing the remainingsteps.

4. Install a new gasket between the exhaust manifold
and exhaust tube. Secure the flange connector to
the manifold using 5/16-18 inch capscrews and
lock washers.
5. Attach the inlet of the muffler to the exhaust tube
using a 1-112 inch U-bolt type automotive muffler
clamp. Make certain that the muffler inlet pipe overlaps the exhaust tube a minimum of 1-1/2 inches
(38 mm).
6. Place the muffler strap on the muffler and position it
below the cutout in the bottom of the generator set
drip tray. Fasten the strap to the set strap bracket
using 1/4-20 screw and lock washer. Tighten the
strap around the muffler using a 1/4-20screw, lock
washers and nut.
7. If replacing the original tailpipe, refer to the Tailpipe
Recommendationssections for selecting and locating the tailpipe. Attach the tailpipe to the outlet end
of the muffler. Secure it using a 1-3/8 U-bolt type
automotive muffler clamp.
8. Supportthe tailpipe using a shock mounted support
hanger with clamp.

Inhalation of exhaust gas can result
lprevent
AWAR"G1
in severepersonalinjury or death. To
exhaust leaks, install all gaskets, Clamps,

To prevent excessive vibration

straps, and hardware as specified. See Tailpipe
Recommendations in this section.

1. Loosen the muffler clamp at the muffler inlet (see
Figure 6-2) and remove the muffler support bracket
screws.
2. Remove the two 1/4-20 screws and lock washers,
and muffler and tailpipe assembly.
Completion of the remaining steps requires that the generator
set be partially removedfrom the vehicle. Refer to Preparing to
Service(Section 5)fortheset removalprocedures.For LPG sels
also perform the procedure for purging LP from the fuel line.

3. Remove the cooling system scroll and noise shield
(see Cooling System in this section) to provide
access to the exhaust manifold.
4. Removethe four exhaust manifold screwsand liftoff
the exhaust manifold and the two manifold gaskets.
Assembly Procedure:

1 -muffler and tailpipetransfer
to the vehicle, mount
hanger brackets directly above

1. Install the exhaust manifold using new gaskets and

tighten the four manifold screws to the specified
torque.
2. Replace the noise shield and scroll (refer to the
Cooling System section).

fhe component being support, NOT at an angle.
9. Run the generator set for five minutes. Check the
entire exhaust system for leaks or excessive noise.
Repair any leaks immediately.

If no other service is required, install the generator set in the
vehicle beforecompletingthe remaining steps.

Fire can cause severe personal
lAWAR"Gl
injury or death. Do not operate
the generator set when vehicle is parked in high

3. Place a U-bolt type automotive muffler clamp
(marked 1-114) in position on the exhaust manifold
(near elbow) prior to installing the muffler.
4. Place the muffler in position on the set, making
certain that the muffler inlet pipe overlaps the
exhaust manifold a minimum of 1-1/2 inches (38

grass or brush.

u

1

mm).

6-6

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by any means, is strictly prohibited.

Exs1120-1

1/4-20 SCREWS

FIGURE 6-2. UNDERFLOOR MOUNT EXHAUST SYSTEM

5. Installthe two 1/4-20 screws and lock washers that
secure the muffler support bracket to the set and
tighten the muffler clamp.

9. Clean the spark arrester muffler every 100 hours of
operation. Remove the 1/8-inch pipe plug in the
bottom ofthe muffler and run theset for five minutes.
Then replace the pipe plug. Inspect the exhaust
system for leaks at least every eight hours of running time.

To prevent excessive vibration
B'
transfer to the vehicle, mount
muffler and tailpipehanger brackets directly above
the component being supported and NOT at an
angle.

t

6. If replacing the original tailpipe, refer to the Tailpipe
Recommendationssectionsto select and locatethe
tailpipe. Attach tailpipe to outlet end of muffler and
secure using a U-bolt type and automotive muffler
clamp (marked 1-3/8) ONLY.
7. Support the tailpipe using ashock mounted support
hanger with clamp.

Tailpipe Recommendations
Tailpipes are supplied by the RV manufacturerand must
meet several design specifications to provide safe
generator set operation. If replacing the tailpipe, make
certain the replacement part is the same size and configuration as the original part. Refer to the following
guidelines for selecting and locating the tailpipe. Also,
refer to recommendations in Installation Manual.
Inhalation
exhaust gases can
liEEESl
result in severe personal injury or
death. Exhaustgases can enter the coach interior if the
of

8. Run the generator set for five minutes and check the
entire exhaust system for leaks or excessive noise.

tailpipe is damaged, missing, or improperly installed.
Be sure to follow the recommended exhaust system
replacement procedures.

fire can cause severe personal
injury or death. Do not operate
generator set when vehicleis parked in high grass
or brush.

0

6-7

Use 1-318 inch ID., 18 gauge, rigid steel tubing for
tailpipe. Do not use flexible exhaust tailpipe,
because it isvulnerable to road shock and vibration.
Redistribution or publication of this document
by any means, is strictly prohibited.

Inhalation of carbon monoxide can
lEEiEI
result in severe personal injury
death. Never use dischargedcoolingair for heating the

Install an exhaust tailpipe at least 3 inches (76 mm)
away from the fuel tank and from any combustible
material. If 3 inches clearance cannot be maintained, install heat shielding between the tailpipe
and the fuel tank or any combustible material, to
prevent excessive heating.
0

or

vehicle interior, because discharged cooling air can
contain poisonous exhaust gases.

Do NOT terminate the exhaust tailpipe in these
positions:

A. Under a window, door, or any opening that
might allow exhaust gases to enter the vehicle
interior.
B. Ahead of or underneath the generator compartment air intake, which might recirculate
exhaust gases. Terminate the tailpipe at the rear
of the compartment air intake if possible.
C. Under the fuel tank fill spout, so spilled fuel
cannot be ignited by a hot tailpipe.
D. Under the vehicle, so exhaust gases cannot
enter the vehicle interior through small openings in the underside of the vehicle.
0

v

Extend the tailpipe at least one inch (25 mm) beyond
the perimeter of the vehicle. Direct exhaust gases
down and away from the vehicle, and away from
windows, doors, or compartment openings.

A'R"
Y-1609-2

FIGURE 6-3 COOLINGAIRFLOW

The size of the generator compartment air inlet (see
Specifications)determines the air flow rate. The air inlet
and discharge openings must remain free of any
obstructions, to avoid restricting airflow. Regularly
remove any dirt, dust, or debris clogging the duct openings. Remove any dirt lodged between the cooling fins
on the engine block and cylinder heads. If the fins are
dirty, heat transfer is greatly reduced, and overheating
can occur.

Do not connect the generator set exhaust tailpipe to
the vehicle exhaust system. Exhaust gases will be
forced into the non-running engine, and might be
released through the carburetor air inlet. Water
vapor from the exhaust might also damage the nonrunning engine.

COOLING SYSTEM
Emerald generator sets use the Vacu-Flo cooling system to provide a constant air flow over the engine and
generator, to minimize heat buildup. A flywheel fan
draws cool air in from the generator end of thecompartment (see Figure 6-3). This air passesover the cooling fins on the engine, absorbing the heat. Heated air is
discharged through the opening in the bottom of the
generator set housing.

The cooling system consists of:
0 Noise shield
Cylinder air housings
0 Scroll
Flywheel
0 Scroll backplate

6-8

Redistribution or publication of this document
by any means, is strictly prohibited.

8. Tighten the puller center screw until the flywheel

Cooling System Disassembly
Procedure

comes loose. Remove the puller, flywheel center
screw, and washer. Inspect the flywheel, and
replace it if any air vanes are missing.

Contact with hot engine parts can
liEE@l
personal injury- The genset
should be shut down and allowed to cool before
cause

9. Remove the lead from the low oil pressure cutoff

switch.
10. Remove the exhaust manifold (see Exhaust System
in this section).

performing this procedure.
b

1. Remove the muffler and tail pipe assembly (see
Exhaust System section) to access the cooling
system.
2. Remove the capscrews that secure the noise shield
(see Figure 6-4) to the engine. Lift off the noise
shield.
3. Remove the three nuts along the lower edge of the
scroll that hold the fan guard to the scroll.
4. Remove the capscrews that fasten the scroll to the
backplate and lift it away from the scroll.
,NOISE

11. Remove the capscrewsthat securethe backplateto

the engine. Lift off the backplate.
12. Use a brush or low pressure compressed air to
remove any dirt or debris that may be lodged on the
engine cooling fins.

FLYWHEEL PULLER

SHIELD

JACK
SCREW

CYLINDER
AIR HOUSINGS

I

k

SCROLL

FLYWHEEL
CAP SCREW

U
cs-1000

I

FIGURE 6-5. FLYWHEEL PULLER

Cooling System Assembly Procedure

To reassemble the cooling system, perform the
assembly steps in reverse order. When installing the
flywheel, align its keyway with the woodruff key on the
crankshaft. Use non-hardening sealer on the flywheel
capscrew threads, and tighten them to the specified
torque. Refer to the Exhaust System section of this
manual to install the exhaust manifold, muffler, and
tailpipe.

cs-1274

/
FAN GUARD

FLYWHEEL

FIGURE

6-4.

COOLING SYSTEM

5. Remove the screws that fasten the cylinder air
housings to the backplate and cylinder heads. Lift
off the air housings.
6. Loosen the flywheel capscrew and back it out
several turns.
7. Attach the puller tool to the flywheel (see Figure
6-5). The tool has two jack screws that fit into the
holes tapped in the flywheel.

1-

6-9

Generator set overheating can result
in engine damage. To avoid this,
never operate the generator set with any cooring
system components removed.

Redistribution or publication of this document
by any means, is strictly prohibited.

ELECTRONIC IGNITION SYSTEM
(Begin Spec G)

SECTION A-A

The electronic ignition system eliminates the breaker
points and condenser of the conventional ignition system. In normal use, the electronic ignition system components should require little or no service or
maintenance.

Ignition System Components
0

Ignition rotor
Ignition module
Ignition coil
Sparkplugs
Wiring

Ignition Rotor
The ignition rotor is attached to the engine crankshaft. It
contains a magnet which rotates past the ignition
module inside the generator adapter. The ends have
opposite magnetic polarity (north and south). One pole
switches on the ignition module, and the other pole
switches it off, once each revolution of the crankshaft.
The ignition rotor should not normally require replacement during the life of the genset.

v

Ignition Module
The ignition module is mounted to the generator/engine adapter, as illustrated in Figure 6-6. It is an electronic switch in the primary circuit of the ignition coil. It is
switched on and off once each revolution by the rotor,
sending a pulse of the proper amplitude and duration to
the ignition coil to be stepped up to high voltage, to fire
the spark plugs. The ignition module contains no userserviceable parts.
Testing Ignition Module:
1. Remove the spark plugs and fan scroll (Figure 6-4)

so that the engine can be turned by hand.

ES-1862

FIGURE 6-6. IGNITION MODULE AND ROTOR

Ignition Module and Rotor Replacement:

The ignition rotor and ignition module are located inside
the generator housing. When the stator in its housing
has been removed, the ignition rotor can be removed/
replaced on the crankshaft, and the ignition module can
be removed/replaced on the generator adapter housing as follows.

2. Connect the positive (+) side of a voltmeter to the
negative (-) terminal of the ignition coil (the larger of

Ignition Rotor Removal/Replacement:

the two screw terminals) and the negative (-)side of
the voltmeter to engine ground.
3. Removeall leadsfromthe positive(+)terminal of the
coil.
4. Use a jumper to connect the ignition module lead
(the one just removed from the coil) to the battery
positive (+) terminal.

To remove the ignition rotor, simply pry it off using a
dull-edged pry bar or other implement. To install the
ignition rotor, place it over the end of the crankshaft,
align the key on the rotor with the corresponding slot in
the end of the crankshaft, and tap the rotor gently into
place.

5. Rotatethe flywheel clockwise by hand and measure
the resultant voltage.
6. If the voltage does not switch from about 1 volt to
about 12 volts and back again to about 1 volt with
each full revolution, the ignition module is defective.

Ignition Module Removal/Replacement:

6-10

1. Unscrew the red and black wiresextending from the
ignition module to the ignition coil. Make certain to
note which wire attaches to which terminal on the
coil.

.(

Redistribution or publication of this document
by any means, is strictly prohibited.

2. Unscrew the two screws holding the ignition

1. Make certain that no gasoline fumes or other flam-

module bracket in place on the generator adapter.
3. When the ignition module is loose, pull the red and
black wires through the gap in the generator
adapter.
4. To replace the module, perform the steps listed
above in reverse order. Be sure to assemblethe new
module to the bracket as shown in Figure 6-6, Section A-A. The studs on the bracket must point
toward the generator end of the set, when
assembled and installed.

2.
3.
4.

5.

mablefumes are present. Park thevehicle in a wellventilated area, and leave the set compartment door
open for several minutes before performing this test.
Remove a spark plug.
Reconnect the spark plug wire to the spark plug.
Ground the spark plug to bare engine metal.
Crank the engine.

A strong spark should appear between the plug center
electrode and the side electrode. A weak spark means
that the coil or wiring may be defective.

Ignition Coil
The ignition coil (Figure 6-7) is a transformer that steps
up the battery voltage to about 20,000 volts, firing the
spark plug.

Direct Testing Coil With OhmmetecThecoil is removed
from the circuit to perform this test.
1. Remove all wires attached to the ignition coil.
2. Remove the coil from the engine.
3. Inspect the terminals for corrosion, looseness,
cracks, dents and other damage. Look for carbon
runners around the high voltage terminals. (These
indicate electrical leakage.) Replace a damaged or
leaking coil.
4. Clean the outside of the coil with a cloth dampened
in parts-cleaning solvent.
5. Measure resistance in the primary circuit: connect
the ohmmeter leads to the positive (+) and negative
(-) terminals on the coil. This resistance should be
between 3.74 and 4.57 ohms. Replace the coil if the
resistance is higher: high resistance indicates an
open circuit or a poor connection inside the coil.

Keep all ignition coil terminals and connections clean
and secure. Check for loose seams, dents, punctures,
and mechanicaldamage. If ignition is poor and the other
ignition components are not at fault, test the coil as
described below. Makecertain of coil polarity: the negative (-) terminal connects to the ignition module (black
lead), and the positive (+)terminal connects to the ignition module (black lead), and the positive (+) terminal
connects to a battery positive (+) source within the control, to the ignitionmodule (red lead), and to filter capacitor C4.

6. Measure resistance in the secondary circuit;
connect the ohmmeter leads to the two highvoltage
terminals (see Figure 6-8). This resistance should
be between 17.45 Kohms and 19.8 Kohms.
Replace the coil if it is not within this specification.
Lower resistance indicates a shorted secondary
winding, and higher resistance indicates the coil
has excessive internal resistance or an open circuit.

WINDING

ES-1863

FIGURE 6-7. IGNITION COIL

-

Ignition Coil Quick Test: This test checks the coil with
the rest of the ignition system.
Gasoline vapor is extremely flammaIBWAR"GJ
ble, and can result in severe personal
injury or death if ignited. Make certain that no gasoline
or other flammable fumes are present. Park the vehicle
in a well-ventilated area, and leave the generator set
compartment door open for several minutes before
performing this test.
Use extreme care when performing
this test procedure. To avoid shock,
do not hold the plug without adequate insulation.

Es-1864

FIGURE 6-8. TESTING COIL SECONDARY

6- 11

Redistribution or publication of this document
by any means, is strictly prohibited.

Spark Plugs
Gasoline is extremely flammable.
Severe personal injury or death can
result if it is accidentally ignited. Eliminateall possible
sources of ignition including fire, flame, spark, pilot
light, arc-producing equipment or other ignition sources before performing this procedure.

IaWARNlNGI

Spark plug problems: Remove and inspect the spark
plugs at the intervals listed in the operator's manual.
Carefully examining the plug can often determine the
source of an engine problem.

The plugs and coil secondary are grounded to the
engine, completing a circuit to the battery. When the
ignition rotor passes the ignition module, it causes the
module to ground its B+ connection, sending a lowvoltage pulse through the coil primary. A high-voltage
pulse is induced in the ignition coil secondary, firing the
spark plug.
Check all low voltage wiring for loose connections and
breaks in the insulation.Clean all terminalsand connections, and use an ohmmeter to test them for continuity.
Use a megger (high-range ohmmeter) to check for
breaks in the plug wire insulation.

One plug carbonfouled:Check foran open ignition
cable or low compression.
Black soot deposits: Check for faulty choke operation, overly rich fuel mixture, or dirty air filter.

Oil fouled: Check for faulty crankcase breather,
worn rings, or worn valve guides.

Burned or overheated: Check for leaking intake
manifold gaskets or lean fuel mixture.
Chipped insulator: Check for advanced timing.
Bend only the side electrode when setting the gap.
Splash fouled: Check for accumulated combustion
chamber deposits. Refer to the Cyhder Headsection of this manual.
Light tan or gray deposits: Normal plug color.

S

*

BREAKER IGNITION SYSTEM
(Prior to Spec G)
The ignition system consists of the following elements:
0
0

0
0
0

Breaker points
Condenser
Ignition coil
Spark plugs
Wiring

This section provides service and adjustment proceduresfor the ignitionsystem. Refer to the Specificafions
section for the correct dimensions for adjustment.

Breaker Points and Condenser
The breaker points and condenser are mounted on the
engine block. Asmall plunger rides on an ignition cam at
the end of the camshaft. This plunger actuates the
points, which open and close twice with every revolution of the camshaft. The point gap setting determines
when the points will open, and consequently, determines ignition timing. If the timing is retarded too far,
efficiency is reduced. If it is advanced too much, overheating results.
The condenser prevents arcing across the opening
breaker points, to extend point life. An open condenser
causes a weak spark and rapid point wear, and must be
replaced. A shorted condenser allows no spark. A new
condenser is supplied with the engine tune-up kit.
Replace the condenser when replacing the points.

\
E51374

FIGURE 6-9. CHECKING PLUG GAP

Breaker Point Replacement/
Adjustment Procedure

Ignition Wiring
The ignition system wiring includes:

Make ignitionadjustments with theenginecold andat rest. Donotiile
the points.

Low voltage wiring from B+ to the ignition module.
Low voltage wiring from the ignition module to the
ignition coil primary winding.
High voltage wiring from the ignition coil secondary
winding to the spark plugs.

6-12

I

Disconnectthe negative (-) battery cable at the battery terminal.
Remove the breaker box cover clip and lift off the
breaker box cover.
Remove the spark plugs, to permit easy rotation of
the engine and generator assembly. Use a socket
wrench to turn the rotor through-bolt clockwise
until the breaker point gap is open as far as possible.
Redistribution or publication of this document
by any means, is strictly prohibited.

4. Disconnect the condenser and ignition lead wires at

5.
6.
7.

8.

screw A (Figure 6-10).
Remove the condenser, mounted outside breaker
points box on engine adapter flange.
Remove the breaker points mounting screws (B)
and lift out the point assembly.
Replace the condenser and point assembly and
install in a reverse order of removal.
Use an allen head wrench to adjust set screw C to
obtain the gap setting specified in the Specifications section. Measure the point gap with a flat
thickness gauge. (SeeFigure 6-10).
Make sure feeler gauge is clean and free of any grease, oil or
dirt.

HIGH
VOLTAGE TERMINAL

SECONDARYWINDING
PRIMARY
WINDING

The timing is adjusted during initial engine assembly and is fixed by the point gap adjustment. No
other adjustment or alignment is necessary.
9. Replace the point box cover and hold-down wire,
spark plugs, and spark plug leads.
10. Connect negative (-) battery cable to negative battery terminal.

IRON CORE

ES-lWI

FIGURE 6-11. IGNITION COIL
CONDENSER
LEAD WIRE

Ignition Coil Quick Test: This test checks the coil with
the rest of the ignition system.

POINT GAP

Gasoline vapor is extremely flammable, and can result in severe personal injury or deafh if ignited. Make certain that no
gasoline or other flammable fumes are present. Park
the vehicle in a well-ventilated area, and leave the
generator set compartment door open for several minutes before performing this test.

IGiTlON

LEAD WIRE

Use extreme care when performing
LBWARNI
N
G?
this test procedure. To avoid shock,
do not hold the plug without adequate insulation.

V
B

FIGURE 6-10.

ES-1529-1

1. Make certain that no gasoline fumes or other flammable fumes are present. Park the vehicle in a wellventilated area, and leave the set compartment door
open for several minutes before performingthis test.
2. Remove a spark plug.
3. Reconnect the spark plug wire to the spark plug.
4. Ground the spark plug to bare engine metal.
5. Crank the engine.

BREAKER POINTS

Ignition Coil
c

The ignition coil (Figure 6-11)is a transformer that steps
up the battery voltage to approximately 20,000 volts, to
fire the spark plug.
Keep all ignition coil terminals and connections clean
and secure. Check for loose seams, dents, punctures,
and other mechanical damage. If ignition is poor and
other ignition components are not at fault, test the coil as
described below. Make certain of coil polarity;the negative (-) terminal connects to the breaker points, and the
positive (+) terminal connects to a battery positive (+)
source within the control.

A strong spark should appear between the plug center
electrode and the side electrode. A weak spark means
that the coil or wiring may be defective.

6-13

Redistribution or publication of this document
by any means, is strictly prohibited.

Direct Tesfing Coil With Ohmmefer: The coil is removed
from the circuit to perform this test.
1. Remove all wires attached to the ignition coil.
2. Remove the coil from the engine.
3. Inspectthe terminalsfor corrosion, looseness, cracks,
dents and other damage. Look for carbon runners
around the high voltage terminals. (These indicate
electrical leakage.) Replace a damaged or leaking
coil.
4. Clean the outside of the coil with a cloth dampened in
parts-cleaning solvent
5. Measureresistance in the primary circuit: connect the
ohmmeter leads to the positive (+) and negative (-)
terminals on the coil. This resistance should be
between 3.87 and 4.73 ohms. Replace the coil if the
resistance is higher: high resistance indicates an
open circuit or a poor connection inside the coil.

Wiring
The ignition system wiring includes:
One positive (B+) wire, which conducts low voltage
from the battery to the primary winding of the coil.
One negative (-) wire, which conducts low voltage to
the points and condenser.
0

Two wires which carry the high voltage from the
secondary coil winding to the spark plugs. The plugs
and coil secondary are grounded to the engine. The
ignition coil primary (low voltage side) is grounded
when the breaker points close.

*

Check all low voltage wiring for loose connections and
breaks in the insulation. Clean all terminals and connections, and use an ohmmeterto test them for continuity. Use
a megger (high-range ohmmeter) to check for breaks in
the plug wire insulation.

6. Measure resistance in the secondary circuit; connect
the ohmmeter leads to the two high voltage terminals
(see Figure 6-12). This resistanceshould be between
12.6 and 15.4 k ohms. Replacethe coil if it is not within
this specification. Lower resistance indicates a
shorted secondary winding, and higher resistance
indicatesthe coil has excessive internal resistanceor
an open circuit

CRANKCASE VENTILATION SYSTEM
The crankcase breather prevents pressure from building up in the crankcase. It preventsoil contamination by
routing moisture, gasoline vapors and other harmful
blow-by materials from the crankcase to the carburetor
and combustion chamber. A sticky crankcase breather
can cause oil leaks, high oil consumption, rough idle,
reduced engine power and rapid formation of sludge
and varnish in the engine and oil in the breaker point
box.
The crankcase breather is vented directly below the generator set.
For this reason, the generator set should only be used in environments where oily vapor and dust do not create a problem.

+ OHMMETER

Crankcase breather vapor contains
poisonous carbon monoxide which
can cause personal injury or death. Do not run the
generator set while parked unless fhe undercarriageis
exposed foa steady airflow.

ES-1373

FIGURE 6-12. TESTING COIL SECONDARY

Spark Plugs
Spark plug inspection is described under Electronic Ignition.

6-14

Redistribution or publication of this document
by any means, is strictly prohibited.

Crankcase Breather Service Procedure
Oil leaks at the seals may mean that the crankcase is
pressurized. Use the following procedure to eliminate
this condition.
1. Removethe breather tube from the valve cover (see

Figure 6-13).

7

1 cause
Over-tightening the valve cover can
an air leak, allowing dirf to

enter the engine. Be careful not to dist0f-f the valve

cover when fighfening.

COMBUSTION CHAMBER
Examinethe spark plugs, and test cylinder compression
to determine the condition of the valves, pistons, piston
rings, and cylinders.

c

BREATHER HOSE

\f--7

1. Start the generator set and allow it to warm up.
2. Stop the generator set. Remove and inspect the
spark plugs (see Ignition System in this section).
3. Insert the compression gauge in one spark plug
hole.
4. Place the throttle and choke in full open position.
5. Crank the engine and note the compression
reading.
6. Stop cranking and perform steps 3 through 5 on the
other cylinder.

ip

HEX HEAD

FLAT
WASHER
VALVE
COVER

Cylinder Compression Check

/

fl-

-"OSECLAMP

\

/

._

i

PACK

Refer to the Specifications section for compression
pressures. There may be variations due to equipment,
temperature, atmospheric conditions and altitude.
These pressures apply to a warm engine at cranking
speed (about 300 r/min). If further inspection is necessary, refer to Engine Block Assembly section.

-

GOVERNOR
The governor controls engine speed, which directly
affects the voltage output and frequency of the generator. An increase in engine speed will cause a corresponding increase in generator voltage and frequency. A
decrease in engine speed will cause a corresponding
decrease in generator voltage and frequency. The governor tries to maintain a constant engine speed under
changing load conditions so that generator voltageand
frequency do not vary.

REED VALVE*

c-1101

FIGURE 6-13. CRANKCASE BREATHER

2-Removethe valve cover, pack,springr washer* reed
valve, and breather baffle.
3. Clean all parts in solvent.

*

Most parts cleaning solvents are
kpersonal
i E iinjury
E lifflammable
and can result in severe
used improperly. Follow the solvent
manufacturer's recommendations when cleaning
parts.

il

The reed valve must be flat and uncreased. Assemble
the valve using a new gasket. Do not overtighten the
valve cover capscrew.
The reed valve must be assembled as shown in Figure
6-9, with a washer on top and the breather baffle on the
bottom.

6-15

Preliminary Governor Adjustment
Before adjusting the governor system, make Sure that
the length of the governor rod is correct. Makethis static
adjustment with the genset cold. Refer to Figure 6-14..
1. Loosenthe jam nut at the ball joint end of the governor rod.
2. Disconnect the plastic ball joint from the ball stud.
3. With the carburetor throttle fully open and the governor rod in its full counterclockwise position,
adjust the governor rod length so that the hole in the
ball joint aligns with the ball stud.
4. Turn the ball joint in (shorter) one full turn.
5. While holding the ball socket in the vertical position,
reconnect the ball joint to the ball stud and tighten
the jam nut.
Redistribution or publication of this document
by any means, is strictly prohibited.

Governor Adjustment
Before making further governor adjustments, run the
unit about 10 minutes under light load to reach normal
operating temperature. If governor is completely out of
adjustment, make a preliminary adjustment at no-load
to first attain a safe voltage and speed operating range.

Refer to Figure 6-14if you areadjustinga spec H set. For sets prior to
spec H, refer to Figure 6-15.

Adjustments to the governor should be made in the
following sequence.

Voltage/frequency-sensitive equipment such as VCR's, televisions, and
computers, may be damaged by power line frequency
variations. Some solid-state devices are powered
whenever connected to an AC outlet even if the device
is not in actual operation. For this reason, disconnect
all devices which are voltage or frequency-sensitive
before attempting any carburetor/governor adjustments. If disconnecting the devices is not possible,
open the circuit breaker@)at the distribution panel or
at the generator set, if so equipped.

@%@!I

Equipment required:
Digital frequency/voltmeter with 0.3% frequency, 0.5%
voltage accuracy. Recommended: Fluke 8060A or 85
series.
Digital ammeter. Recommended: Beekman 4410
Load bank with 8 kW (minimum capacity) variable 600
watt section.

A

1. The carburetor fuel mixture screws must be correctly adjusted before governor adjustments are
made. If the carburetor needs adjusting, refer to the
Mixture Screw Adjustments in this section before
making any adjustments to the governor.

rl

w

Touching hot exhaust pipes or
moving parts can result in
severe personal injury. Use extreme caution when
making adjustments while the engine is running.

l3HESl

2. Run the genset at least 15 minutes at 50% to 75% of
its rated load. Then remove the load and let the set
stabilizefor 10 to 15 seconds. Make certain that the
set is running with no load.
3. With the unit operating at no load, adjust the governor speed nut to 50 f 2 Hz (50 Hz sets: 40+ 2 Hz)
while checking that the idle stop screw is not contacting the throttle lever. Then adjust the idle stop
screw to increasethe engine speed to 55f 1 Hz (50
hz sets: 45f 1 Hz).
4. Run the generator set with no load, and adjust the
speed adjustment nut to the following frequency:

GOVERNOR
SP,FZING

I

n

50 Hz, 110/220 volts

51.5-52.5 HZ

BALL AND
SOCKET

GOVERNOR ROD
GOVERNOR SPEED

DETAIL A

w

COTTER PIN

WASHERS

n

THROTTLE

SC-1629

\

GOVERNOR ROD

FIGURE 6-14. GOVERNOR ADJUSTMENT (SPEC H)

6-16

Redistribution or publication of this document
by any means, is strictly prohibited.

Check the frequency and voltage at no load. Frequency and voltage should stay within the limits
shown in Table 6-1. Then apply rated load to the
generator set, and check frequency and voltage.
Calculate "droop" by subtracting the full-load frequency from the no-load frequency.
If the droop is greater than the specified range,
adjust the governor spring towards the governor
shaft by turning the adjusting screw counterclockwise 1 to 2 turns. If the droop is less than the minimum specified, or if the set is hunting, adjust the
governor spring away from the governor shaft by
turning the adjusting screw clockwise 1 to 2 turns.
Recheck the no load speed setting and readjust if
needed. Reapply rated load and check thegovernor
droop. Repeat theseadjustmentsuntil droop and no
load frequency readings are within the correct
ranges and the set is stable (no hunting) at any load
from no load to rated load.

-

FUEL SYSTEM GASOLINE
The fuel system must be properly adjusted and in
good condition for efficient generator set operation.
Main components of the fuel system include:
0
0

0
0
0

Air filter assembly
Carburetor
Choke
Intake manifold
Fuel filter
Fuel pump
Air preheater

Fuel systems present the hazard of
lignited,
eWAR"G1
fire or explosion if accidentally
which can cause severe personal injury or
death. Eliminate all possible ignition sources such as
open flame, sparks, cigarettes, pilot lights, and arcproducing machinery and switches from the workarea
when performing the following procedures.

TABLE 6-1.
CHECKING VOLTAGE AND SPEEDlFREQUENCY

Air Intake Assembly
The air intake assembly (Figure 6-16) consists of:

(10,2-Wire)
Voltage
Maximum No-Load
Minimum Full-Load

112

SpeedlFrequency
Maximum No-Load
Speed (rlmin)
Frequency (Hz)

63

1575
52.5

1740
58

1440
48

1890

Minimum Full-Load
Speed (r/min)
Frequency (Hz)

I Droop (Hz)

Air cleaner housing
Air filter
Air cleaner adapter
Choke assembly

I

2-4

I

Disassembly Procedure:
Contact with hot engine parts can
cause personal injury. The genset
should be shut down and allowed to cool before performing this procedure.

1.5 - 3.5

1. Remove the crankcase breather hose and air pre-

SPEED ADJUSTMENT NUT

heater hose from the air cleaner housing.
2. Remove the air cleaner housing center capscrew
and lift off the housing and air filter.
3. Removethe chokecover retainingnut and liftoff the
choke cover.
4. Disconnect the choke lead wires at the choke
terminals.
5. Remove the three capscrews that secure the air
cleaner adapter to the carburetor and lift off the
adapter. Note thatthe choke linkage must be disengaged from the choke assembly as the adapter is
removed.
6. Remove the two capscrews that secure the choke
bracket to the adapter. Lift off the choke assembly.

FS-1613

SENSITIVITY
ADJUSTMENT SCREW

Assemble Procedure: Reverse the order of disassembly. Use a new gasket between the adapter and the
carburetor.

FIGURE 6-15. GOVERNOR ADJUSTMENT
(PRIOR TO SPEC H)

6-17

Redistribution or publication of this document
by any means, is strictly prohibited.

CRANKCASE BREATHER

AIR PREHEATER
HOSE

/

CARBURETOR

'\

\ A
W

AIR FILTER

n
AIR CLEANER

ADAPTER

CHOKE
COVER
FS-1609-3

FIGURE 6-16. AIR INTAKE ASSEMBLY

Carburetor and Intake Manifold
Assembly

2. Disconnect the fuel line and governor control linkage from the carburetor.
3. Remove the intake manifold capscrews and lift off
the carburetor air preheater. Lift off the carburetor
and intake manifold as an assembly.
4. Remove the two intake manifold gaskets and plug
the intake ports with a rag to prevent loose parts
from accidentally entering the ports.
5. Removethetwocapscrewsthat secure the carburetor and choke pull-off assemblyto the intake manifold. Disengagethe choke pull-off linkage from the
carburetor, and carefully separate the carburetor
from the intake manifold.

The carburetor and intake manifold assembly (Figure
6-17) consists of:
0

Intake manifold
Choke pull-off assembly
Air preheaters
Carburetor
Fuel filter

Gasoline vapor is extremely flammable, and can result in severe personalinjury or death if ignited. Make certain all fuelline
openings are plugged fo prevent gasoline vapor from
accumulating. Eliminate all possible sources of ignition including fire, flame, spark, pilot light,
arc-producing equipment or other ignition sources
before working in fhis area.

Assembly Procedure: Reverse the order of the disassembly steps. Use new gaskets between the intake
manifold and the engine, and between the intake manifold and the carburetor. Do not use sealer on the
gaskets. Tighten the intake manifold capscrews to the
specified torque.

.
..

Disassembly Procedure:
1. Remove theair intakeassembly, asdescribed in the
Air Intake Assembly section.

6-18

Redistribution or publication of this document
by any means, is strictly prohibited.

URETOR

DETAILOf

FIGURE 6-17. CARBURETOR AND INTAKE MANIFOLD ASSEMBLY

Carburetor Fuel Mixture Adjustments
The most common cause of poor carburetion is incorrect adjustment of the idle or main mixture adjustments.
Significantvariation from the correct settings may result
in serious engine trouble. An overly rich mixture not only
wastes fuel, but can increase engine wear by washing
the lubricant from the cylinder walls and diluting the
crankcase oil. An overly lean mixture results in a loss of
power, flat spots in acceleration, and a greatertendency
to burn valves and spark plugs.

c

4

Voltage/ frequency-sensitive
equipmentsuch as VCRs, televisions, computers, etc. may be damaged by power
line frequency variations. Some solid-state devices are powered whenever connected to an AC
ouflet even if the device is not in actual operation.
For this reason, disconnect all devices which are
voltage or frequency-sensitive before attempting
any carburetor/governor adjustments. If disconnecting the devices is not possible, open the circuit
breaker@)at the distributionpanelor at the generator set, if so equipped.

Mixture adjustments should be checked with every
tuneup, and whenever a carburetion problem is suspected. Before adjusting, be sure that the ignition system is working properly, and that the governor is set
correctly. If the carburetor is grossly out of adjustment,
make these preliminary adjustments:

Forcing the mixture adjustment
screws tight will damage the
needle and seat. Turn them in only until light tension can be felt.

1. Turn both mixture screws in until lightly seated.
2. Turn the idle mixture screw out one full turn.

Start the engine and allow it to run about 10 minutes.
Theadjustment screw location is shown in Figure 6-1 8.

3. Turn the main mixture screw out 1-1/4full turns.

6-19

Redistribution or publication of this document
by any means, is strictly prohibited.

Mixture Adjustment Procedure:
1. Stop the set and connect a voltmeter, frequency

meter, and load bank to the generator output leads.
2. Start the generator set and apply a full load. Adjust
the governor speed adjustmentnut to obtain 59 (49)
f 2 Hz.
3. Remove the plastic cap over the main adjustment
limiter (cap). Turn the main adjustment screw
inward until the voltage or frequency drops. Then
turn it outward until the voltage or frequency drops
again. Locate the point where voltage and frequency are highest. From this point, turn the main
adjustment screw out another 1/4turn. Replacethe
main adjustment lever (limiter cap), so it aligns with
the proper attitude position.

IDLE
ADJUSTMENT
SCREW
CAP

LE
ST

’

THROTTLE
LEVER

THROTTLE
STOP
SCREW
(IDLEADJUST)

4. Remove the load and verify that frequency is within
62-63 Hz (on 50 Hz sets, 51.5 - 52.5 Hz). Adjust the
governor speed adjustment nut if necessary to
obtain required frequency.
5. Remove the idle adjustment screw cap (limiter).
Turn the idle adjustment screw inward until voltage
and frequency drop and the engine begins to run
rough or starts hunting. Back outthe idle adjustment
screw as required for smoothest operation without
hunting. Replace the idle adjustment screw cap
(limiter) with the lever located at mid position
between lever stops.
Or, for more accuratesetting with CO meter (if available); after setting idle and main adjustmentscrews,
but before installation of plastic limiter cap, set to the
following (with engine running): no-load: 6 to 8%
CO,rated load: 7 to 10% CO. Install limiter caps as
instructed above.
6. With the unit at no-load, adjust the governor speed
nut to 50 f 2 Hz (50 Hz sets; 40f2 Hz). With the
throttle lever against the idle stop screw, adjust the
idle stop screw to 55f 1 Hz (50 Hz sets 45+ 1 Hz).
7. Readjust the no-load speed to 62-63 Hz (on 50 Hz
sets, 51.5-52.5 Hz) and observe the stability of the
set. Set the voltage and frequency and adjust the
sensitivity of the governor as specified under Governor in this section. Add and remove a full load
several times to make certain the set does not bog
down or hunt.

Y

”

M
- AN
I
ADJUSTMENT
SCREW
FS-1691-1

FIGURE 6-18. CARBURETOR FUEL ADJUSTMENTS

-

IDLE MIXTURE

IDLE SPEED
STOP SCREW

THROTTLE
LEVER

-

\

ALTITUDE
ADJUSTMENT
(MAIN MIXTURE)

FIGURE 6-18a. CARBURETOR FUEL ADJUSTMENTS
(SPEC K GENSET)

6-20

Redistribution or publication of this document
by any means, is strictly prohibited.

Carburetor Disassembly Procedure
1. Remove the air cleaner adapter and the automatic
choke assembly.
2. Remove the throttle and choke plate retaining
screws, then remove the choke plates. Pull out the
throttle and choke shafts, being careful not to damage the Teflon coating on certain throttle shafts.
3. Remove the main and idle mixture screw
assemblies.
4. Separate the lower section of the carburetor (fuel
bowl) from the upper section (fuel bowl cover) of the
carburetor.
5. Note the position of the float assembly parts. Slide
out the retaining pin and removethe floatassembly,
springs or clips, and the needle valve.
6. Unscrew and remove the needle valve seat

Carburetor Overhaul
Carburetion problemsthat cannot be corrected by mixture or float adjustments are often caused by blocked
fuel passages or worn internal parts. The most effective
remedy is a complete carburetor overhaul.

t

Overhauling a carburetor means complete disassembly, thorough cleaning, and replacing worn parts. Carburetor repair kits include new gaskets and replacements for the parts that wear out.
Carefullynotethe carburetor position while removingall
parts, for correct reassembly. Read and understand
these procedures before beginning. Carburetor components are illustrated in Figure 6-19.
Gasoline is extremely flammable.
@@%@
Severe personal injury or death can
result if it is accidentallyignited. Eliminateallpossible

Carburetor Cleaning and Repair Procedure

sources of ignition including fire, flame, spark, pilot
light, cigarettes, arc-producing equipment or other
ignition sources before performing this procedure.

1. Soak all metal components to be reused in carburetor cleaner. Do not soak rubber or plastic parts.
Follow the instructions on the cleaner container.

Remove the carburetor and intake manifold assembly,
as specified in the Carburetor and Intake Manifold
Assembly description in this section. Remove the carburetor from the intake manifold. Disassemble it using
the following procedure.
CHOKE SHAFT

jaWAR"G1

flammable and can result in
severe personal injury if used improperly.

IDLE

ADJUPTIAENT

s!

~

THROTTLE PLATE

THROTTLE
STOPSCREW

\
v

CHOKE PLATE

x

3

/

/

Mostparts cleaningsoluentsare

THROTTLE
SHAFT

2. Removethe carbon from the carburetor bore, especially where the throttle and choke plates seat. Be
certain not to plug the idle or main fuel port.
3. Blow out all passages with compressed air. Do not
use wire or any cleaning utensil that might widen
critical passages. Wear goggles while performing
this procedure.
4. Examine any needle valves not included in the
repair kit, and replace if damaged (Figure 6-20).
Replace the float if it is damaged or contains fuel.
5. Check the choke and throttle shafts for excessive
play in their bore. Replace them if necessary.
6. Replace old components with the new parts from
the repair kit.

FUEL INLET
VALVE

GASKET

IDA
AND WEAR

BUOYANCY

I

SPRING

OCCURHERE

FLOAT

MAIN ADJUSTMENT
SCREW ASSEMBLY

\

@

B

B

FIGURE 6-20. MIXTURE NEEDLE INSPECTION

FS-1604-1

FIGURE 6-19. CARBURETOR OVERHAUL

6-21

Redistribution or publication of this document
by any means, is strictly prohibited.

Reassembly and Installation Procedure
0.59-0.63 IN.
(15-16 mm)

1. Slide in the throttle shaftand install the throttle plate

if7-

BEND TAB
TO(DJUST

using new screws (if included in the repair kit).

..

Center the plate in the throttle bore before tightening the screws. To do this, back the throttle stop
screw out as necessary, and close the throttle lever.
Seat the plate by gently tapping it with a small
screwdriver, then tighten the screws. Install the
choke shaft and plate in the same manner.
2. Installthe idle mixture screw assembly. Turn in the
screws until lightly seated, then turn it out one turn.

t

Forcing the mixture adjustment
screws tight will damage the
needle and seat. Turn in only until light tension is
felt.

--qY

BOWL FLANGE
~~

GASKET

TAB C~NTACTING
HEAD OF PIN. WITH
FULL WEIGHT OF FLOAT
COMPRESSING INLET
VALVE SPRING
FS-1611

FIGURE 6-22. FLOAT LEVEL

3. Install the needle valve and seat, fuel bowl gasket,
and float assembly. Make sure that the float moves
freely without binding (see Figure 6-21), and that all
clips and springs are placed correctly.

5. Install the float bowl and main mixture screw
assembly. Make sure the index line on thefloat bowl
altitude scale lines up with the arrowhead cast in the
mating flange of the carburetor. Turn the screw in
until lightly seated and then turn it out 1-1/4 turns.
Forcing the mixture adjustment
screws tight will damage the
needle and seat. Turn in only until tension can be
felt.

SlTlON HOOK
DER TANG ON

6. When carburetor is installed on set, make final idle
and main mixture adjustments as described in the
Carburetor Fuel Mixture Adjustment section.

Choke

FS-1610

POSITION OF SPRING
AFTER INSTALLATION

FIGURE 6-21. FLOAT INSTALLATION

4. Invert the float and needle valve assembly. Check
the float level as follows: measurefrom the carburetor housing to the far side (bottom) of the float (see
Figure 6-22). The full weight of the float should rest
on the needle valve and spring. If the setting is
incorrect, remove the float and bend the tab to
adjust. Bend the float only at the point indicated.
Attempting adjustments with the
float assembly installed can
damage the inlet needle andseaf. Remove the float
assembly before making adjustments.

The choke assembly consists of a bi-metal coil, an
electric heating element, and a choke pulloff diaphragm.
The coil is connectedto the choke shaft. Itturns the shaft
to hold the choke platenearly closed when the engine is
cold. When the engine starts, vacuum from the intake
manifold causes the pulloff diaphragm to pull in and
partially open the choke. As the engine runs, the heating
element receives electric current. Heatfrom theelement
causes the bi-metal strip to coil, turning the choke shaft
to gradually open the choke plate, and keepingthe plate
open while the engine is running.
The choke becomes very hot during

(BWARNINGI normal operation, and can cause

severe burns if touched. Do not remove the choke
cover while the set is operating.

-

If the engine starts but runs rough and gives off black
smoke after a minute or two of operation, the choke is
setfortoo richamixture. Iftheengine starts but sputters
or stops before it warms up, the choke is set for too lean
a mixture.

-

6-22

Redistribution or publication of this document
by any means, is strictly prohibited.

Choke Adjustment: Table 6-2 lists choke settings for
various ambient temperatures. Stop the set and allow it
to cool before adjusting the choke.

4. Refer to Table 6-2 to determine the number of

degrees the element cover must be rotated clockwise from the reference position. The marks on the
choke housing are spaced at 5" intervals.
5. Rotate the element cover as specified,then tighten
the cover mounting screws.
6. Move the choke lever to test its operation. The lever
should return to the free position when released
from the open position, without sticking or binding.
7. Installthe plasticchoke cover and tighten the center
mounting unit.

1. Remove the plastic choke cover (see Figure 6-23)
and loosen the heating element cover screws.
2. Rotate the heating element until the choke plate is
halfway open.
3. Slowly rotate the cover counterclockwise while
tapping the carburetor choke lever to make it
bounce. Continue until the lever no longer bounces.
This is the fully-closed (reference) position.

Choke Replacement

TABLE 6-2.
CHOKE ADJUSTMENTS
Ambient Air
Temperature

Rotation From
Reference Mark*

40°F (4°C)
45OF (7°C)
50°F (10°C)
55°F (13°C)
60°F (16°C)
65°F (18°C)
70°F (21"C)
75°F (24°C)
80°F (27°C)
85°F (29°C)
90°F (32°C)
95°F (35°C)
100°F (38°C)

0"
4OCW
8"CW
12"CW
16"CW
2O"CW
24"CW
27"CW
32"CW
35"CW
39"CW
43"CW
47"CW

If the choke does not open, removethe protective plastic
cover and check the heating element. The heating element cover should heat up after afew minutes of operation. If the element cover remains cool, startthe set, then
use an AC voltmeter to check the terminals on the cover.
If roughly 20 VAC is not present, check for opens or
shorts in the control wiring. Check for an open or damaged element.
If voltage is present, stop the set and removethe heating
element cover. Inspectthe heating element and replace
it if burned out or broken. Also inspect the bi-metal coil
and replace it if it is damaged or binding in the housing.

*Each mark on choke housing equals 5"
angular rotation.

PLASTIC COVER

XFS-1605

FIGURE 6-23. CHOKE ASSEMBLY

6-23

Redistribution or publication of this document
by any means, is strictly prohibited.

3. Apply light finger pressure against the choke lever
to take up all free play in the pulloff linkage (see
Figure 6-25).
4. Check and correct the alignment of the diaphragm
stem, pulloff linkage, and slot in the choke lever,
viewing them from above.
5. Measure the distance between the choke plate and
the bottom of the carburetor at the point indicated in
Figure6-25. There should be 0.39 to 0.43 inches (9.9
to 10.9 mm) clearance here; if necessary, bend the
diaphragm mounting bracket to reach this
clearance.
6. Move the choke lever back and forth to verify that it
does not bind or stick.
7. Remove the vacuum supply from the diaphragm.
Install the filter assembly on the carburetor.

When installing a new bi-metal strip, maintain the original direction of the spiral (see Figure 6-24). The outer
tab must point in a clockwise direction. Make sure that
the coil sits squarely in the housing, and that the inner
end of the coil engages the slot in the choke shaft. The
slotted tang on the element cover must engage the
bi-metal strip.

\

FS-1606

c)

Fuel Pump

OUTER TAB

FIGURE 6-24. BI-METAL SPIRAL STRIP

Choke Pulloff Diaphragm Adjustment: The choke pulloff diaphragm partially opens the choke plate after
engine startup. This inhibits flooding, and promotes
smooth engine operation as the set warms up.

Choke Pulloff DiaphragmAdjustment
Procedure
1. Removethe air intake assembly, as described in Air
lnfake Assembly in this section, to accessthe choke

plate.
2. Disconnect the diaphragm hose from the intake
manifold. Apply 4 to 18 inches (13.5 to 60.8 kPa) Hg
vacuum to the diaphragm.

PULL OFF LINKAGE

PULL OFF DIAPHRAGM

All gasoline-fueled generator sets use electric fuel
pumps. The electric pump has an integral shutoff valve
that preventsfuel flow to the carburetor when the set is
idle. If the pump malfunctions or supplies insufficient
fuel, test and repair/replace the pump as described
below.

1-

Do not substitute an automotive fuel
pump for the standard Onansupplied fuel pump. Other pumps’ output pressure is
much higher, and can cause carburetortooding or fuel
leakage, creating a fire hazard.

Pump Test Procedure
1. Removethe fuel line from the pump outlet. Install a
pressure gauge in the line.
2. Press the Start switch and hold it for several
seconds, until the pressure reading is constant. A
normal pump produces 4 to 5 psi (27.5 to 34.4 kPa).
Pressure should stay constant or drop off very
slowly.
If the pressure is below 3-1 12 psi (17.2 kPa), replacethe
fuel pump.

If the pressure is zero, check the electrical connections,
then recheck the pressure reading.

DISTANCE

/

1

There are no serviceable components in the fuel pump.
Refer to the generator set Parts Manuals and replace
the pump with an Onan-supplied unit.
DIAPHRAGM MTG BRKT
BEND HERE

Do not tamper with the seal at the
center of the mounting bracket on the
side of the pump, because it retains the dry gas which
surrounds the electrical system. Electrical system
components are not serviceable.

L

FIGURE 6-25. CHOKE PULL-OFF DIAPHRAGM

6-24

Redistribution or publication of this document
by any means, is strictly prohibited.

-

Choke Spec K

1. Apply a vacuum of at least 4 inches (100 rnm) of

Figure6-25a illustratesthe Spec K choke components for
gasoline carburetors. Replace faulty choke components
and reassemble as shown. Adjust the choke breaker assembly each time it is assembledto the carburetor, as follows:

mercury to fully pull in the choke breaker arm.
2. Insert
a
inch (8.6 mm) drill rod
the
choke plate and the carburetor throat.
3. If necessary, bendthe linkat the point shown untilthe
lip of the choke plate just touches the drill rod. Use
two pliers to bend the link.

FS-1872-1s

-

FIGURE 625a. CHOKE ASSEMBLY SPEC K

6-24a

Redistribution or publication of this document
by any means, is strictly prohibited.

-

FUEL SYSTEM LPG LIQUID
WITHDRAWAL
The fuel system must be properly adjusted and in good
condition. Components of the fuel system are:
0
0

0
0
0
0
0

Air cleaner assembly
Carburetor
Intake manifold
Fuel filter
Solenoid valve
Vaporizer
Two-stage regulator

LPG generator sets that use a liquid withdrawal system
are intended to share the vehicle LPG fuel tank. The
LPG fuel tank must be designed with adip tube to permit
liquid fuel withdrawal. This section provides basic
information about LPG fuel systems and service procedures for each fuel system component

LPG Liquid Withdrawal Fuel Systems
LPG liquid withdrawal fuel systems typically operate at
pressures as high as 200 psi (1379 kPa) when the
ambient temperature is 11OOF (43.3"C). Because of the
high pressure, special precautions must be taken to
avoid releasing large quantities of highly flammable LP
gas when servicing the fuel system. Use the procedure
described below to purge the fuel system of LP gas
before servicing any fuel system components.
LP gas (Propane) is extremely flammable. Severe personal injury or
death can result if it is accidentally ignited. fliminafe
all fire, flame, spark, pilot light, arc-producing equipment or other ignition sources before purging LP gas
from the fuel system. Provide adequate ventilation to
dissipate LP gas as it is released.

l&i@EW

LPG Purging Pressure
1. Open the AC load circuit breaker and close the
shutoff valve at the fuel tank.
2. Start the generator set and run it until it stopsfor lack
of fuel.
3. Crank the set a few times after it stops, to make sure
the fuel system is purged of fuel.

If the generator set cannot be operated, do the following:
1. Move the vehicle to a well-ventilated outdoor location, far from fire or flame.
2. Disconnect the vehicle negative (-) battery cable
and the generator set negative(-) battery cable from
their battery terminals.
3. Close fuel shutoff valves at the fuel tank for the
generator set fuel supply system and any other fuel
supply system. Close the fuel shutoff valves for any
auxiliary equipment.
4. Slightly open the fuel line (flexible section) at the
solenoid valve, and allow the LP gas to slowly
escape. Do not open the fitting widely; a large quantity of gas may be released.
5. Disconnect the fuel supply hose from the carburetor, and hold it clear of the set.
6. Press in and hold the primer button on the regulator
to release LP gas from the set fuel system.
7. When gas can no longer be heard escaping from
the open end of the fuel supply hose, reconnectthe
hose to the carburetor.

J

Carburetor, Air Filter, and Intake
Manifold Assembly
The carburetor, air filter, and intake manifold assembly
(Figure 6-26) consists of:
0

0
0
0

Air cleaner housing
Air filter
Air cleaner adapter
K5 relay assembly
Carburetor
Intake Manifold

Disassembly Procedure:
1. Remove the crankcase breather hose from the air
cleaner housing.
2. Remove the air cleaner housing center capscrew
and lift off the housing and air filter.
3. Disconnectthe lead wires from the K5 relay terminals.
4. Remove the three capscrews that secure the air
cleaner adapter and lift off the relay assembly.
5. Remove the two capscrews that secure the K5 relay
bracket to the adapter and liftoff the relay assembly.
6. Disconnectthe fuel hose and governor control linkage from the carburetor.
7. Remove the two capscrewsthat securethe carburetor to the intake manifold. Lift off the carburetor.

6-25

-

Redistribution or publication of this document
by any means, is strictly prohibited.

8. Remove the intake manifold, as follows:

A. Disconnect the flexible fuel supply line from the
fuel vaporizer.
B. Remove the exhaust
(as described in
this section) to provide clearance
to lift off the
intake manifold.

Assembly: Reverse the order of the disassembly steps.
Use new gaskets between the exhaust manifold and
engine, the intake manifold and engine, and the carburetor and intake manifold. Tighten the exhaust and
intake manifold capscrews to the specified torque.
Tighten the fuel vaporizer fittings and checks for leaks.

the fuel vaporizer
1- fenablingcracks Bending
tubing weakens the metal,
form. Do not bend the vapoio
rizer tubing to remove the intake manifold.

C. Remove the intake manifold capscrews and lift
off the intake manifold.
D. Remove the two intake manifold gaskets from
the block and plug the intake ports with clean
rags to prevent loose parts from accidentally
entering the ports.

CRANKCASE
BREATHER HOSE

n

AIR CLEANER HOUSING

I

/

FS-1612-2

GASKET
AIR CLEANER ADAPTER

/--

K5 RELAY

GASKET
J

,

FIGURE 6-26. CARBURETOR, AIR FILTER AND INTAKE MANIFOLD ASSEMBLY

6-26

Redistribution or publication of this document
by any means, is strictly prohibited.

Adjustment Procedure:

Carburetor Mixture Screw Adjustments

1. Stop the set and connect a voltmeter, frequency

Vo/tage/irequency-sensitive
equipment such as VCRs, televisions,
computers, etc. may be damaged by power line frequency variations. Some solid-state devices are
powered whenever connected to an AC output even if
the device is not in actual operation. For this reason,
disconnect a// devices that are voltage or irequencysensitive before attempting any carburetor/governor
adjustments. If disconnectingthe devices is notpossible, open the circuit breaker@)at the distributionpanel
or at the generator set, if so equipped.

lacAunoNI

LPG carburetors have three adjustment screws:
0

0
0

The throttle stop screw sets the width of the throttle
plate opening when the throttle is pulled back to the
closed position.
The idle adjustment screw controls the fuel mixture
when the set is operating at no load.
The main adjustment screw controls the fuel mixture when the set is operating at full load.

No other adjustments are necessary with an LPG carburetor, because there are no float or choke adjustments.

Do not make these adjustments until the ignitionsystem,
governor, and other fuel system components have been
checked for correct operation. If the carburetor is
grossly out of adjustment, turn the mixture screws in
until they are lightly seated, then turn the main adjustment screw out 2-1 /2 (+ 114) turns and the idle adjustment screw out 1 (* 114) turn. This provides a rough
preliminary adjustment.
forcing the mixture adjustment
screws tight will damage the needle
and seat. Turn in only until light tension can be felt.

Start the engine and allow itto run for 10 minutesat light
load. Figure 6-27 illustrates the location of the adjustment screws.
IDLE ADJUSTMENT
SCREW
THROTTLE STOP
SCREW

/

meter, and load bank to the generator output leads.
2. Start the generator set and apply a full load. Adjust
the governor speed adjustment nut, if necessary, to
obtain 59 (49) 2 Hz.
3. Turn the main adjustment screw inward until the
voltage or frequency drops, then outward until the
voltage or frequency drops again. Set the main
adjustmentscrew at the point where thevoltageand
frequency are highest.
4. Remove the load. Adjust the governor speed
adjustment nut if necessary, to obtain 62 (51.5) f 1
Hz.
5. Turn the idleadjustmentscrew inward until thevoltage and frequency drop and the engine begins to
run rough or starts hunting. Back out the idle
adjustment screw until the engine runs smoothly
without hunting.

*

w

"

Or for a more accurate setting with CO meter (if
available), after setting idle and main adjustment
screws, but before installation of plastic limiter cap,
setto the following (with engine running); no-load: 6
to 8% CO, rated load: 7 to 10% CO. Install limiter
caps as instructed above.
6. With unit at no-load, adjust governor speed nut to 50
5 2 Hz (50 Hz sets: 40 t- 2 Hz). With the throttle lever
against the idle stop screw, adjust the stop screw to
55 f 1 Hz (50 Hz sets: 45f.1 Hz).
7. Readjust no-load speed to 62 (51.5) f 1 Hz and
observe the stability of the set. Set the voltage and
frequency and adjust the sensitivity of the governor
as specified in the Governor section. Add and
remove a half-load several times, to make certain
the set does not bog down or hunt.

Carburetor Overhaul
Carburetor problems that cannot be corrected by mixture adjustments may be caused by dirt in fuel passages,
or by worn internal parts. Normally, the carburetor
should seldom require cleaning, because LP gas vaporizes completely before reaching the carburetor, leaving
no residue. However,a bad fuel supply or fuel filter may
let dirt or oil through to the carburetor. This may mean
that the carburetor should be cleaned to restore satisfactory operation.
Overhaulingthe carburetor involves its complete disassembly, thorough cleaning, and replacement of worn
parts. Carburetor repair kits are available that supply
new gaskets and replacementparts for the components
subject to wear.

MAIN ADJUSTMENT
SCREW

L.

Note the position of all components while removing
them, for correct reassembly. See Figure 6-28 for component designations.
FS-1601

FIGURE 6-27. MIXTURE SCREW ADJUSTMENTS

6-27

Redistribution or publication of this document
by any means, is strictly prohibited.

Removal and Disassembly Procedures:
1. Remove the carburetor from the intake manifold, as
described in the Carburetor, Air Filter, and Intake
Manifold Assembly section.
Mostparts cleaningsolvents are
f/ammab/eandcanresuMinsevere
personal injury if used improperly. Follow the
manufacturer's recommendations when cleaning
parts.
2. Remove the throttle stop collar and throttle stop
lever from the end of the throttle shaft.
3. Remove the throttle plate retaining screws and
throttle plate. Remove the dust seals from the throttle shaft, and carefully pull out the throttle shaft.
4. Remove main and idle mixture screw assemblies.
5. Separatethe lower section (bowl)of carburetorfrom
the upper section (bowl cover).

Cleaning and Repair Procedures:

1. Soak all metal components that have not been

2.
3.

4.
5.

replaced in carburetor cleaner. Do not soak any
non-metal parts: they may bedamaged by the cleaning solution. Follow the cleaner manufacturer's
recommendations.
Clean all carbon from the throttle bore, especially
where the throttle plate seats. Be careful not to plug
the idle or main fuel ports.
Blow out all passages with low pressure (30 kPa)
compressedair. Do not use wire or otherobjectsfor
cleaning that might increase the size of critical
passages.
Check the condition of the mixturescrews(see Figure 6-29) and replace them if worn or damaged.
Replaceall old components, seals, and gaskets with
new parts included in the kit.

THROTTLE STOP SCREW

\

IDLE ADJUSTMENTSCREW

1
DAMAGE AND WEAR
OCCUR HERE

FS-1483

FIGURE 6-29. MIXTURE NEEDLE INSPECTION

Reassembly and installation Procedure:

I
THROITLE SHAFT

BOWL
GASKET

V
'

BOWL

1. Slide in the throttle shaft and install the throttle plate
using new screws (if furnished in the repair kit).
Center the plate in the throttle bore before tightening the screws. To do this, move the throttle lever to
the completely closed position. Seat the plate by
gently tapping on it with a small screwdriver, then
tighten the screws. Install the seal, the throttle stop
lever, and the collar on the throttle shaft.

Q

FS-1602

FIGURE 6-28. CARBURETOR OVERHAUL

6-28

Redistribution or publication of this document
by any means, is strictly prohibited.

2. Installthe idleand main adjustmentscrews and turn
them in until lightly seated. For preliminary settings,
turn the idlescrew out 1 (k1/4) turn and main screw
out 2-1 12 (21/4) turns.
Forcing the mixfure adjusfmenf
screws fight will damage the
needle and seat. Turn fhese screws in only unfil
lighf tension is felt.

A regulator that has been operated, then stored for any
l e n g t h of t i m e may r e q u i r e rebuilding or
replacement. Diaphragms and gaskets tend to dry,
shrink, and harden with time. Use the test procedure
specified in the Regulator Testsection to check regulator operation, then rebuild or replaceas required. Repair
kits include detailed and illustrated installation
instructions.
*

3. Join the upper and lower sections of the carburetor,
and install the bowl plug and washer.
4. When the carburetor is installed on the set, make
final adjustments to mixture screws as specified in
the Carburetor MixtureScrew Adjustmentssection.

Regulator
A two-stage regulator (see Figure 6-30) delivers vaporized LPG fuel to the carburetor. The primary stage of
the regulator receives LP gas at container pressureand
reduces itto the low pressure required for set operation.
The secondary stage of the regulator restricts fuel flow
through the regulator until the vacuum from the engine
creates a demandfor fuel. Fuel flowsthrough the regulator only when the engine is cranking or operation; it
stops flowing when the engine is stopped.

1

The regulator should require little attention if the set is
used on a regular basis, and operated on clean, high
quality fuel. Most regulator malfunctions can be traced
to two sources:

0

Hardened diaphragms and seats due to extended
periods of non-use.
Dirt or foreign matter embedded in valves and valve
seats.

XFS-1600

FIGURE 6-31. REGULATOR DISASSEMBLY

FS-1598

FIGURE 6-30. LP GAS REGULATOR

6-29

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by any means, is strictly prohibited.

A regulator with granules of foreign matter embedded in

the secondary seat may cause inconsistent starting or
idling. Foreign matter dissolved in the LPG can form
granules as the fuel is vaporized. Remove the regulator
front cover and diaphragm assembly (see Figure 6-31)
to check for dirt or oil deposits. If granules are
embedded in the rubber of the secondary valve, wash
the valve and seat clean.

Fuel Filter
The fuel filter (seeFigure6-33) removes solid impurities
such as rust and scale from the LP gas before they can
clog the regulator and carburetor. A magnet within the
filter housing traps iron and rust particles, and a filter
element traps nonmagnetic particles. The fuel filter
operates at container pressure; it must be carefully
assembled to prevent leakage.

Regulator Test Procedure:
Use compressed air and an automobile fuel pressure
gauge to test the regulator.

FILTER ELEMENT

1. Attach the pressure gauge to the test port on the
back of the regulator as shown in Figure 6-32.
2. Attach a pressure hose to the inlet opening, and
open the air pressure valve.
3. If the primary seal is sound, the gauge should read
approximately 1-1/2 psi (10.3 kPa), and the pressure should remain constant.A fluctuating pressure
reading indicates a bad primary seat
4. Close the air pressure valve and observe the pressuregauge. The pressureshould remain constant. If
the pressure reading drops, the secondary seat is
leaking.
Ifthe regulator does not pass either test, it must be
rebuilt or replaced.

O-RING SEAL

0

-c

INLETOPENING

FIGURE 6-33. FUEL FILTER

Disassembly and Cleaning Procedure:
LPG is extremely flammable. Severe
personal injury or death can result if
it is accidentally ignited. Eliminate allpossible sources
of ignition including fire, flame, spark, pilot light, arcproducing equipment or other ignition sources before
performing this procedure.
FS-1599

FIGURE 6-32. REGULATOR TEST

6-30

1. Remove the four capscrews and lock washers that
hold the filter bowl to the filter body.
2. Separate the filter bowl from the filter body, and
discard the O-ring seal.
3. Remove the nut and washer from the center stud
and pull out the filter element.
4. If the filter element is clogged, wash the element in
kerosene. Blow it dry with low pressure (30 psi1207
kPa) compressed air. Replace the filter element if
damaged.

Redistribution or publication of this document
by any means, is strictly prohibited.

5. Wipe the center stud magnet clean of any rust or
scale particles that have collected.
6. Install a clean filter element using two new gaskets,
and securely tighten the center stud nut.
7. Place a new O-ring in the filter bowl sealing groove.
8. Align the reference mark on the filter bowl with the
reference mark on the filter body. Install capscrews
(4) and lock washers (4). Tighten the capscrews to
56 to74 in-lbs(6.5 to 8.3 Nom) torque. When the fuel
system is pressurized, check the filter for leaks.

Solenoid Valve
The solenoid valve (see Figure 6-34) providesa positive
fuel shutoff when the generator set is stopped. The
solenoid must be energized for fuel to flow to the regulator. A faulty valve must be replaced.
To bench-test the valve, connect battery positive (E+)to
the top terminal, and battery negative (B-) to the
grounded terminal. The plunger assembly should withdraw and open the valve when the solenoid is energized. Replace the solenoid valve if it does not operate
properly.

Special precautions must be taken to avoid releasing
large quantitiesof highly flammableLP gas when servicing the fuel system. Use the LPG Purging Procedure
described in the LPG Liquid Withdrawal Fuel System
section to purge the fuel system of LP gas before servicing any fuel system components.
Service procedures for the air cleaner assembly, carburetor, intake manifold and solenoid valve are described in the previous sections. The following service
procedure appliesto the LPG vapor withdrawal demand
regulator, which is unique to the vapor withdrawal
system.

4

The fuel supply line pressureto the demand regulator 01the generator set fuel system components must be in the range of 6 to 8 ounces
per square inch (equivalent to 10 to 14 inches water column).

The fuel supply from the primaryregulatorto the generator setfuel system components must be dedicated to the
generator set only, not shared with any appliances.

LP gas presents fhe hazard of fire or
explosion and if is poisonous. These
hazards can result in severe personal injury or death. If
flameout occurs with an unvenfed appliance, LP gas
can accumulate inside the vehicle and create a safety
hazard. /f the generator sef fuelsupply line is shared by
any vehicle appliances, do not continue with any
furfher service procedures. Obtain a copy of the
lnstrucfion Sheet 665 -Assembly Instructions for the
Installation of LP Vapor Kif tor Use with BGE and NHE
Generator Sets. Compare the instruction sheet procedures and applicable codes to the generafor set and
fuel supply system installation. Correct as necessary
before continuing service work.

-

LP Fuel Supply at Carburetor Adjustment
Open the fuel supply shutoff valveatthesupplytankand
proceed as follows:
1. Loosen the lock nut on the gas adjustment screw
(located near the LP gas inlet (see Figure 6-35).

ES-1553

FIGURE 6-34. SOLENOID VALVE

2. Turn the LP gas adjustment screw inward until
seated.
3. Push the generator set start button, while the set is
cranking, slowly turn the adjusting screw out counterclockwise (1/4 to 1/2 turn) until set starts. This
adjustment is critical for proper operation of the set.
If the set does not start, reseat the gas adjustment
screw and repeat the adjustment procedure.
4. If the set still does not start, refer to the Regulator
Adjustment informationthat follows, and check that
main fuel supply system is supplying fuel to the
generator set solenoid valve.

-

FUEL SYSTEM
LPG VAPOR WITHDRAWAL
The LPG vapor withdrawal fuel system is very similar to
the liquid withdrawal system. Main components of the
LPG vapor withdrawal fuel system are:
0

0

Air cleaner assembly
Carburetor
Intake manifold
Solenoid valve
Demand regulator (externally mounted)

For satisfactory operation, it may be necessary to reset
the gas adjustment screw due to variations in the BTU
content of local LP gas supplies and for changes in the
ambient temperature. The idle and main adjustment
screws on the gasoline carburetor will have no effect
during LP gas operation.

6-31

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by any means, is strictly prohibited.

2. Connect a manometer that reads up to 14 inches
(356 mm)of water column to the test hole. One inch

of water equals 0.58 ounce/square inch (250 Pa).
3. Energize the solenoid shutoff valve by connecting
its insulated lead to a battery positive (B+)source.

*WARN"

LP gas presents the hazard of
fire or exp/osion and it is poi-

sonous. These hazards can result in severe personal injury or death. Provide adequate ventilation
while adjusting regulator to prevent any possible
accumulation of LP gas.

c

4. Remove the gas supply hose from the regulator

/

outlet, then open the fuel tank shutoff valve. Gas
should not come from the regulator outlet during
testing, because of the closing action of the regulator valve.
5. Alternately cover and uncover the regulator outlet
with the palm of your hand while at the same time
observing the manometer. If the regulator closes
completely, the manometer will hold a steady reading. If the manometer reading drops slightly each
time you remove your hand, it indicates the regulator is not locking off properly. To adjust, turn the
adjusting screw inward until the manometer reading holds constant when you repeatedly cover and
uncoverthe regulator outlet. Failureto lock off indicates too high an incoming pressureor a dirty regulator valve and seat.

LOOSEN
LOCKNUT

GAS
ADJUSTMENT
SCREW

FS-1765

FIGURE 6-35. ADJUSTING FUEL FLOW AT CARBURETOR

Demand Regulator Adjustment Procedure
Difficult startingmay be caused by slow cranking due to
a weak battery. Temperatures below 32OF/OoC
increasethe load on the battery at cranking speed. Low
cranking speed in turn inhibits proper intakevacuumfor
starting.
If the generator set fails to start or operate properly, and
the starting or ignition systems are not at fault, check
and adjust the demand regulator inlet pressure and the
regulator lockoff as follows:

A soap bubble placed over the
lrately
aWARNl
N
Gl
regulator outlet will not accutest regulator closing and will cause the very

1. Close the gas supply valve at the fuel tank(s) and
remove the 1/ 8 inch pipe plug from the regulator
test hole. See Figure 6-36.

sensitive demand regulator to shut off.
6. Close the gas supply shutoff valve at the fuel tank.

GAS HOSE

AWARNlNG LP gas presents the hazard of

fire or explosion, and it is poisonous. These hazards can result in severe personal injuty or death. Cranking the engine or disconnecting the solenoid valve will create sparks
that can ignite accumulatedgas vapors. Make sure
that any gas vapors, accidentally released during
testing, have been safely and completely dissipated before proceeding.

FS-1108.1

FIGURE 6-36.

7. De-energize the solenoid valve, and reconnect the
solenoid lead to its control lead.
8. Connect the gas supply hose to the regulator outlet
fitting and secure it with a clamp.
9. Remove the manometer, and install a 1/8 inch plug
in the test hole.
10. Verify that the vent hose is properly routed through
the opening in the compartmentfloor,then open the
gas supply shutoff valve.
11. Adjust the gas adjustment screw, as described in
the previous section. Operate the generator set to
test that it starts correctly.

MANOMETER TESTING (IF REQUIRED)

6-32

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by any means, is strictly prohibited.

ELECTRIC STARTER

3. Remove the starter mounting screws. Carefully disengage the starter from the stator housing.
4. Remove the starter through-bolts. Carefully separate the brush end cap housing from the armature
assembly.
5. Uses 1/8to 5/32 inch nail setto remove the roll pin.
(When reassembling, use a new roll pin.) Remove
the return spring, gear and clutch assembly as
required. See Figure 6-38.

Removal and Disassembly Procedure:
1. Disconnect the generator set negative (-) battery

cable from the set starting battery.
2' Disconnect the generator set positive 1('
cable from the starter lug terminal. See Figure 6-37.

.
)

FIGURE 6-37. STARTER

SUPPORT PLASTIC
RETAINERW H
A VlSE OR OTHER
SOUD SURFACE

to 1

USE CARE NOT TO
HAM SPRING RETURN
"LEO" BETWEENTHE Pusnc
RETAlNER a SUPPORT WHEN

DRMNG OUT R O U PIN.

ES-1609

FIGURE 6-38.

DRIVING ROLL PIN OUT

6-33

Redistribution or publication of this document
by any means, is strictly prohibited.

Testing Armature for Grounds: Touch one ohmmeter
lead to a commutator bar, then touch the other lead to
the armature shaft and the core laminations. A low
resistance reading indicates a grounded armature.
Replace a grounded armature with a new one. See
Figure 6-39.

Testing for Opens: Touch one ohmmeter lead to a
commutator bar, then touch the other lead to each of the
other commutator bars in turn. A high resistance indicates an open circuit between the commutator bars and
armature windings. Replace an open armature with a
new one.

Brush Inspection: Measure brushes (Figure 6-41) and
replace them if worn less than 0.425" (11 mm).

b

0.425 INCH
mm) WEAR LIMIT

A

1

t-

1

NEW0.57d INCH
(14.5 mm)

ES-1614

ES-1610

FIGURE 6-41.

FIGURE 6-39. TESTING ARMATURE FOR GROUNDS

BRUSH INSPECTION

Testing forShortsAJsea growler(Figure 6-4O)to locate
shorts in thearmature. Place thearmature in the growler
and hold a thin steel blade (hacksaw blade) parallel to
the core and just above thearmature, whileslowly rotating the armature in the growler. A shorted armature will
cause the blade to vibrate and be attracted to the core.
Replace a shorted armature with a new one.

LER

ES-1615

FIGURE 6-40. TESTING ARMATURE FOR SHORTS

6-34

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by any means, is strictly prohibited.

Assembly

2. Mountthe brush springs on tabsasshown in Figure
6-42.Using a small screwdriver, turn the spring

1. Wipe dirt and oil from starter components using a

counterclockwise to torque it, so the contact loop is
inside the brush holder. The spring should be
pushed down to the mounting tab shoulder.
3. Push the negative brush terminals over the
through-bolt holes on the brush endcap.
4. lnserta positive brush stud intothe hole, and torque
to 25-30in-lb (2.83- 3.39 Nom).
5. Insert asmall screwdriver into the brush spring contact loop to bend the spring back so that each brush
can be inserted into the holder. Be sure that all
brush wires are facing up.

clean cloth; or blow off dirt with filtered lowpressure compressed air.
Oil on armature will damage
starter. Do not immerse bearings in cleaning fluid. Use a brush dipped in clean
engine oil to remove dirt from bearings. Avoid geffing oil on brushes or commutator.

1

w

-

TORQUE TO 5-10 IN-LBS (.57 1.13 Nam)
ORQUE TO 25-30 IN-LBS (2.83-3.39 NDm)
IMPORTANT! THIS INSULATEDSHUNT
MUST BE ROUTED THRU UNINSULATED
SHUNT AS SHOWN TO PREVENT CONTACT
WITH COMMUTATOR IN FINAL ASSEMBLY.

CONTACT LOOP

NEGATIVE BRUSH
TERMINAL

IMPORTANT! SPRING MUST BE ASSEMBLED
ON MOUNTING TAB AS SHOWN.

ES-1612-1

FIGURE 6-42. BRUSH ENDCAP

6-35

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by any means, is strictly prohibited.

6. If the brushes are at least 0.430 inch (10.9 mm) long,

10. Place a spring washer and a flat washer on the
shaft, as shown in Figure 6-44.
11. Placethe mounting bracketon the motor, facing the
exposed end of the sleeve bearing and throughbolt
lead-ins toward the inside of the motor. The flat near
one mounting hole should line up with the positive
stud on the end cap, so the through-bolts can line

rest the brush springs against the sides of the
brushes to keep them clear during armature installation. See Figure 6-43.
7. Place a washer on the commutator end of the shaft,
and put the armature into the brush endcap. Push
the four brushes toward the commutator, making
sure that the springsare correctly positioned on the
brushes. Recheck to be certain that the spring is
pushed all the way down on the mounting tab.
8. Make sure that all brush wires are clear of the commutator, and that uninsulated portions of insulated
wires do not touch the inside of the housing, or
adjacent brush boxes.
9. Placethe magnetic housing over the armature. Hold
down the armature and the end cap using a nut
driver pressed over the end of the shaft.

UP-

12. Insert the through bolts, and torque to 35-45 Ib-in
(3.96-5.09 Nom).
13. Wipe dust from the helix and gear, and apply a light
coat of GE Versilube 322-L to the outside diameter
of the helix, the inside diameter of the gear and the
unchamfered end of the gear. Place the clutch and
helix assemblies on the motor shaft, with flats
engaged in the clutch hole.

ES-1611

FIGURE 6-43. RESTING BRUSH SPRING ON BRUSH SIDE

6-36

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by any means, is strictly prohibited.

.

ES-1613

FIGURE 6-44. STARTER ASSEMBLY

14. If the return spring is unassembled,do the following:
A. Place a 1-1 / I 6 inch O.D. washer over the end of
the shaft.
B. With thechamfered sideof theshafl hole facing
up, place a plastic retainer on the shaft and line
up the hole with a hole in the shaft.
C. Support the plastic retainer with a vise or other
solid surface. Using a 5/32 or 118 inch nail set
and hammer, drive in a new roll pin. The pin
should be driven about 1110th of an inch (2.5
mm) from the edge of the plastic retainer, or in
such a way that it is evenly spaced from each
side.

D. Place the spring cover over the top of the plastic
retainer, then place the return spring on top of
the retainer.
E. With a washer placed over the point of the plastic retainer, push the metal retainer into the hole
of the plastic retainer as far as it will go.
15. Mount the starter on the generator stator housing

using capscrews, lockwashers and nuts. Tighten
the mounting screws to 30-33 Ib-ft (41-45 Nom).
16. Connect generator set positive (+) battery cable to
starter terminal. Connect generator set negative (-)
terminal to generator set starting battery.

6-37

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by any means, is strictly prohibited.

Section 7. Control
INTRODUCTION

The following sections describe each component and
how it functions.

The control system governs the following functions:
1

4

0

The control panel assembly consists of:
0 Printed circuit board (Al)
Start/Run/Stop switch (Sl)
0 Fuse(F1)

Starting
Monitoring for fault conditions
Instrumentation
Stopping

This section covers how the control operates, where the
components are located, and basic troubleshooting
procedures.

CONTROL DESCRIPTION
The generator set control consists of the components
listed below (seeFigure 7-1):
0
0
0

0
0
0
0

0
0

0
0
0

Control panel assembly
Printed circuit board (Al)
Start/Run/Stop switch (Sl)
Fuse (FI)
Start solenoid (Kl)
Ignition relay (K5)(LPG units)
Fuel pump (E2) (gasoline units)
Fuel solenoid (E2) (LPG units)
Remote start control (optional)
Circuit breaker(s)
Voltage regulator (VR1)
Terminal board (TBl)

Printed Circuit Board (AI): The printed circuit board
controlsthe engine start, startdisconnect/run, and stop
functions. It is mountedto the rear of the control panel. It
contains wiring harness connections to the engine,
generator, and optional remote start control; the startstop switch (Sl);and the control fuse (Fl).
Start/Run/Stop Switch (SI): S1 is a SPDT rocker
switch which starts and stops the generator set. The
switch returns to the center (run) position when
released. It is mounted on the circuit board, and is not
field-replaceable.

fuse (FI): This 5-amp fuse protects printed circuit
board A1 from overcurrent conditions. It is removable
from the front of the control panel. Sparefuses are inside
the fuse holder, use only Onan-supplied fuses.

SPARK
PLUGS
CHOKE (Hl)
(GASOLINE SETS ONLY)I
ON LPG-FUELEDSETS,
IGNITION RELAY K5 IS
LOCATED HERE

IGNITION COIL (El)

NEGATIVE(-)
BATTERY CONNECTION

C CIRCUIT BREAKERS (CB1, CB2)
NOTE CONFIGURATIONAND
PLACEMENT OF FUEL PUMP
MAY VARY DEPENDING ON
GENSET SPEC LEVEL

REMOTE CONTROL

y

-

START

START/STOP SOLENOID (K1)
SWITCH (Sl)

FIGURE 7-1. BGUNHE GENERATOR SET

7- 1

FUEL PUMP (E2)
(GASOLINE SETS ONLY)
ON LPG-FUELEDSETS,
FUEL SOLENOID (E)
IS LOCATED HERE

!

AUTOCHOKE
FUEL PUMP/
FUSE
(F2) MOUNTED ON
CONTROL BOX

M-1604-14
(modified)

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by any means, is strictly prohibited.

Fuse (F2) (Spec Kgensets):This 5-amp fuse protects
the fuel pump and choke heater circuit. It is mounted on
the front of the control box (see Figure 7-1a).

Remote Start Control (optional)
The remote start control is an optional accessory that
enables the generator set to be operated from a remote
location. The deluxe control includes a running time
meter and battery condition meter.

Control Circuit Breaker(s)
(CB1 and CB2 [if equipped])
AC output from the generator is supplied to circuit
breakers CB1 and CB2, located on the right side of the
control housing. Ampere rating of these breakers may
differ, depending on generator set modeVfrequency.
Refer to the proper Parts Manual when ordering
replacement parts.

F2 FU
HOLD

.

Voltage Regulator (VR1)
The voltage regulator helps provide stable output voltage under varying loads. During initial start of the set,
thevoltage regulator receives DC currentfrom thestarting battery, and begins excitation of the rotor through
leads J4-9/FIl and J4-101F2. After the generator set
starts and runs, it provides AC power to the voltage
regulator (through leads J4-11 /Q1, and J4-12/Q2) for
the excitation system. The AC voltage is rectifiedto DC
voltage, and the proper DC excitation voltage is induced
to the rotor in response to changes in demand.

BRACKET

FIGURE 7-la. AUTOCHOKWFUEL PUMP FUSE F2 LOCATION

The K1 start solenoid opens and closes the circuit
between the starter motor and the battery. The starting
current load requires that the solenoid contacts have a
300-amp contact rating. A single terminal connects to
the 12-volt solenoid coil.Two studs provide connection
points to the battery and starter cables; the battery B+
stud connection protrudes through the control panel to
the outside of the control housing for convenient
access.

Thevoltage regulator is protectedfrom moisture, reducing the risk of component failure. The printed circuit
board control is encased in the regulator housing with a
potting compound, the ends of the 54 wiring harnessare
booted, covering the terminals of capacitor C5
(mounted to the outside of the regulator housing), and
the wiring harness plug-in P4 is treated with a lubricant
prior to connection. More protection is provided by
mounting the voltage regulator assembly inside the
generator control housing.

Ignition Relay (K5) (LPG units)

Terminal Board U B I )

Start Solenoid (KI)

The AC output power leads from the generator (Tl, T2,
T3, and T4) are connected to terminal board TB1.

The K5 ignition relay latchesthe generator set off when
switch S1 is moved to the STOP position. This prevents
the set from restarting when the switch is momentarily
placed in the STOP position,then released.The K5 relay
is located on the choke bracket.

These connections may differ between models. Refer to the proper
Wiring Diagram/Schematic for specific information.

AC power at TB1 terminals is tapped by leads of wiring
harness J4 of voltage regulator VR1, and interconnect
wiring to the circuit breaker(s) CB1 (and CB2, if
equipped). These leads provide generator output to the
voltage regulator for proper voltage regulation, and to
the circuit breaker(s) for power supply to load.

Fuel Pump (E2) (gasoline units)
The E2 fuel pump is initially energized at the same time
the start solenoid K1 is energized by closure of start
relay K4 contacts. After a successful startup, the fuel
pump then receives its current through the contacts of
run relay K3.

1

Fuel Solenoid (E2) (LPG units)
The solenoidvalve providesapositivefuel shutoff whenever the generator set is stopped. The solenoid must be
energized before fuel will flow to the regulator. It is
energized in the same manner, at the same time, as the
fuel pump is energized in gasoline units.

7-2

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by any means, is strictly prohibited.

CONTROL OPERATION

Starter Lockout-Run
When start-stop switch S1 is released and returns to the
center (run) position,the enginecontinuesto run. Relays
K2 (generator relay), K3 (run relay), and K5 (ignition
relay [LPG sets only]) are energized while relays K1
(start solenoid) and K4 (start relay) are de-energized.

The schematic diagram shown in Figure7-2 is intended
as an illustration of the circuit description. However,
when troubleshooting, always refer to the wiring diagram that corresponds to the model and spec numbers
of the generator set.
m

Starting

Energizing K2 opens a set of contacts to de-energize
K4, and closes another set of contacts to connect B+ to
the generator start disconnect/run relay (k3). Energizing K3 closes a set of contacts which provides an alternate B+ circuit to T1 ignition coil and E l fuel pump/fuel
solenoid.

Placing the Start/Run/Stop switch in the Start position
connects battery ground (B-) to the K4 start relay. This
energizes K4, which closes the normally open (N.O.)
contacts that connect battery positive (B+) to the
following:
0

0
0

N.C. contacts of K2 generator relay
Generator voltage regulator
Ignition coil (Tl)
Fuel pump or solenoid valve (E2)
Start solenoid (Kl)

De-energizing K4 opens contacts which de-energize
the K1 start solenoid. De-energizing K1 disconnects B+
from the starter motor, which stops cranking.
Opening these K4 contacts at this time has no effect on
engine operation, because they are in parallel with the
closed K3 contactswhich connect B+to the ignition coil
and the fuel pumplfuel solenoid.

Connecting B+ produces the following control responses:
Flashes the field, to ensure that there is adequate
residual magnetism to induce voltage buildup.

When start-stop switch S1 is releasedand returnsto the
center (run) position, the engine continues to run.
Relays K2 (generator relay), K3 (run relay), and K5 (ignition relay ([LPG sets only]) are energized while relays K2
(start solenoid) and K4 start relay) are de-energized.

Energizesthe ignition coil (Tl), so it can begin producing a spark when ignition moduleS3 is activated
(prior to Spec G, breaker point ignition is used.)

Stopping

Energizes the start solenoid (Kl), which closes its
N.O. contacts in the starter motor circuit.

(LPG units) Energizesthe fuel solenoid (E2), which
allows LPG to flow to the vaporizer and the
regulator.

Moving start-stop switch S1 to the STOP position
grounds resistors R1 and R2 to de-energize run relay
K3. This opens its contacts to disconnect B+ from ignition coil TI, fuel pump/fuel solenoid E2, and (on LPG
sets) ignition relay K5. De-energizing K5 allows its N.C.
contactsto close to ground.This prevents K3 from being
energized, and prevents the set from restarting when
switch S1 is released from the STOP position.

Energizesthe stop latch (ignition) relay (K5) to open
its contacts to ground, which allows run relay K3 to
be energizedthrough closure of oil pressureswitch
S2 after engine startup.

Without ignition orfue1,theengine stops. Asthegenerator output voltage drops, generator relay K2 also deenergizes. All components return to their de-energized
position following set shutdown.

(Gasoline units)Energizesthe fuel pump (E2), which
begins pumping fuel to the carburetor.

Closing the K1 start solenoid contacts connects B+ to
the starter motor. This energizes the starter motor,
which begins to crank the engine to initiate starting.

7-3

Redistribution or publication of this document
by any means, is strictly prohibited.

TESTING CONTROL BOARD AI
Confirm that control board A1 is faulty before replacing
it. Use a DC voltmeter and an ohmmeter to perform the
following tests.
1. Disconnect the negative (-) battery cable.
2. Remove the control box cover (Figure 7-3) and
separate it from control board A1 by removing the
four screws on the back of the board.
3. With an ohmmeter, check for electrical continuity
across each P l / J l and P3/J3 connector on the
control board (Figures 7-2 and 7-4). Replace the
socket portion of each connector that has a measurable resistance (greater than zero ohms) or has
begun to corrode.
4. Reconnect the battery and try to start and run the
set.
5. If the engine does not crank, measure voltage at
connector P1-2 while pressing the panel start
switch (the negative (-) test probe of the voltmeter
should be grounded at connector P1-8). If the voltmeter indicates zero volts, and if fuse F1 is good,
replace control board Al. If the voltmeter indicates
at least 9 volts, the problem is not with the control
board. Go back to the Troubleshooting Guide.
6. If the engine cranks, but does not start, measure
voltage at connectors P3-3 and P3-6 while the
engine is cranking (the negative (-) test probe of the
voltmeter should be grounded at connector P1-8).
Replace control board A1 if the voltmeter indicates
zero volts at either connector. If the voltmeter indicates at least 9 volts at both connectors, the problem is not with the control board. Go back to the
TroubleshootingGuide.

7. If the engine starts, but stops when the Start switch
is released, the problem could be with the low oil
pressure switch or generator (no voltage). Go back
to the Troubleshooting Guide. Replace control
board A1 if the oil pressure switch and generator
are functioning properly.
8. Reassemble the control board and cover.

I '

'.r

61 1 - 1 190

I

Item
VR1

1 DescriDtion of Material
Ignition Coil

S3

Ignition Module
Switch-Low Oil Pressure
Resistor-Battery Charge
Potentiometer

R6
R5

K5

K1
HI
G1
F1
E34

Relav-LPG Onlv

I Relav-Start Solenoid
Fuse-Slow Blow 5A
Spark Plugs

E2

Fuel Pump or Fuel Solenoid
Rectifier-LPG Only

E1
A3
A2

AI
A1

I

Choke-Gasoline Only
Generator

CR9
CB1,2
~4.5
BT1

I

Voltage Regulator

T1
52

I

7-4

r:'

Circuit Breaker (AC Output)

I Capacitor

I Battery - 12V
I Starter Motor

I Remote Control-Standard
I Remote Control - Deluxe
I Control ASSY - NHEINHEL

Control Assy - BGElBGEL

Redistribution or publication of this document
by any means, is strictly prohibited.

8

ES-1775-3

FIGURE 7-3. BGElNHE CONTROL COMPONENTS

FIGURE 7-3a. BGE/NHE CONTROL COMPONENTS (SPEC K)

7-5

Redistribution or publication of this document
by any means, is strictly prohibited.

ES-1774

FIGURE 7-4. BGE/NHE CONTROL P.C.B. ASSEMBLY (AI)

7-5a

Redistribution or publication of this document
by any means, is strictly prohibited.

CONTROL TROUBLESHOOTING
Use the following troubleshooting guide to help locate
problemsrelatedto the control circuits. Figures 7-3 and
7-4 show the location of most of the control
components.

Theschematic diagram shown in Figure 7-2 is intended
as an illustration of the circuit description. However,
when troubleshooting, always refer to the wiring diagram that correspondsto the model and spec numbers
of the generator set.
The troubleshooting guide is divided into sections. After
identifying the problem, refer to the guide for the possible cause and the recommended corrective action.

Many troubleshootingprocedures presenf hazards which can result in severe personal injury or
death. Only qualifiedservicepersonnel with knowledge of fuels, elecfricity, andmachineryhazards
should periorm service procedures. Review safety precautions on inside cover page.

Trouble

Engine Does
Not Crank

I

Corrective Action

Possible Cause
1. Control fuse F1 may be open.

1. Replace fuse F1 if open with
Onan supplied fuse only.

2. If engine cranks at set but not at remote
control panel, fault is due to:
a. PC board P2/J2 connection not
secure.
b. Open circuit in remote control.
c. Remote start switch faulty.

2a. Ensure that wiring harness jack
connections are fully seated to PC board.
b. Check for continuity and correct if
circuit is open.
c. Replace remote start control switch.

3. If engine cranks at remote control panel
but not at set, fault is due to faulty S1
switch.

3. Replace PC board Al.

4. Insufficientvoltage for cranking due to:
(See Low Battery Voltage also.)
a. Battery not charged.
b. Terminal connections loose or dirty.
c. Battery cable too small.

4a. Check condition of battery and recharge
or replace.
b. Clean and tighten all connections at
battery, K l start solenoid, and
motor.
c. Increase cable size.
Short circuiting the
@@@%I
batterv cables can result
in severe personal injiry, Disconnect the

negative (-1 battery cable at fhe battery
terminal before servicing.
5. Connect a voltmeter between terminal S 5a. Tighten solenoid bracket mounting
on the start solenoid and ground. Check
screw.
for battery voltage when S1 is placed in
b. Replace K1 start solenoid.
START position. If voltage is present,
c. Refer to Nectric Starter (Section 6) for
fault is due to:
test and service procedures.
a. K1 relay not grounded.
b. Defective K1 relay.
c. Defective starter.

6. If voltage is not present as described in
step 5 test, fault is due to:
a. Open circuit between K1 relay and
control PC board.
b. Defective control PC board.

7-6

6a. Check for continuity and correct if circuit
is open.
b. Refer to Testing Control BoardA 7.

Redistribution or publication of this document
by any means, is strictly prohibited.

Many troubleshootingprocedures present hazards which can result in severe personal injury or
@@!@%I
death. On/y qualified service personnel with knowledge fuels, electricity, andmachineryhazards
should perform service procedures. Review safety precautions on inside cover page.
of

Trouble
Engine Cranks
But Does Not
Start

Possible Cause

Corrective Action

1. Faulty ignition due to worn or fouled
spark plugs, faulty plug wires,
faulty ignition coil, breaker worn
points*** or faulty ignition module****.

1. Refer to lgnition System (Section 6) for
test and service procedures.

2. Faulty fuel system due to low fuel
level in tank, supply valve not open,
sticking choke*, faulty fuel pump*,
faulty fuel solenoid**, or
carburetor mixture screws
incorrectly adjusted.

2. Refer to Fuel System (Section 6) for test
and service procedures.

3. Connect a voltmeter between positive (+] 3a. Check for continuity and correct if circuit
terminal Ti ignition coil and ground.
Check for battery voltage when S1
is placed in the START position.
If the voltage is not present,
fault is due to:
a. Open circuit between T1 coil
and control.
b. Defective control PC board.

is open.
b. Refer to Testing Control Board A 7.

*Gasoline Sets Only.
**LPG Sets Only.
***Prior to Spec G.
****Spec G and Later.
Engine Starts But
Stops When Start
Switch is
Released

1. Low oil pressure switch S2 not
closing due to:
a. Low oil level.
b. Open circuit between switch and
control.
c. Defective low oil pressure switch.
d. Low oil pressure.

la. Check oil level and add oil if low.
b. Check for continuity and correct if
circuit is open.
c. Replace low oil pressure switch.
d. Refer to Section 6 Troubleshootingfor
procedures to follow.

2**. lgnition relay K5 contacts not opening 2a. Check for continuity and correct if
circuit is open.
due to:
a. K5 relay circuit open.
b. Replace K5 relay.
b. Defective K5 relay.

3. Output voltage from generator not
being supplied to control due to:
a. Open circuit in wiring between
generator and control.
b. No output voltage from generator.
4. Defective control PC board A1 .

3a. Check for continuity and correct if
circuit is open.
b. Refer to Generatorsection for test
and service procedures.
4. Refer to Testing Control Board A 1.

**LPG Sets Only.
c

Low Battery
Voltage

a. Low electrolyte level in battery.
b. Long periods of non-use.

la. Replenish electrolyte and recharge
battery.
b. Connect a separate battery charger to
bring battery up to full charge.

2. Load connected to battery while set
is turned off.

2. Turn off /disconnect load and recharge
battery.

1. Weak or discharged battery due to:

7-7

Redistribution or publication of this document
by any means, is strictly prohibited.

Many troubleshooting procedures present hazards which can result in severe personal injury or
deafh. Only qualifiedservicepersonnel wifhknowledge of fuels, electricity,andmachineryhazards
should perform service procedures. Review safety precautions on inside cover page.

Trouble

.

Engine Starts And
Runs; Then Stops.
Set Restarts
Immediately or Set
Restarts After
Cooling Down

Corrective Action

Possible Cause
1. Fuel level is below generator set fuel
pickup tube or oil level is low.

1. Check fuel and oil levels and refill
as necessary.

2. Dirty fuel filter restricting fuel flow.

2. Refer to Fuel System (Section 6)
for test and service procedures.

3. "Faulty choke operation due to sticking

3. Refer to h e / System (Section 6) for test
and service procedures.

choke linkage, incorrect choke
adjustment, open circuit in wiring
between choke heater and generator,
defective choke heater.
4. *Vapor lock due to:
a. High ambient air temperatures.
b. Faulty fuel pump.

4a. Remove any objects or debris that may
restrict airflow to and from the set
b. Refer to Fuel System (Section 6) for test
and service procedures.

5. ***Breaker points sticking.

5. Replace breaker points.

6. ****Faulty ignition module.

6. Replace ignition module.

7. ***Faulty ignition condenser.

7. Replace condenser.

8. Contaminated fuel.

8. Refill tank with fresh fuel.

*Gasoline Sets Only.
***Prior to Spec G.
****Spec G and Later.
-

REMOTE
CONTROL
(if equipped)
Run Lamp, Time
Meter, or Battery
Condition Meter
Condition Meter
Does Not Operate

1. Open circuit between control board A1
terminal 6 or 5 of remote connector plug
P2/J2 and terminal 6 or 5 on start-stop
switch S2.

1. Check for continuity and correct if open.

2. Open circuit between ground terminals
on lamp or meters and terminal 1 on
remote start-stop switch.

2. Check for continuity and correct if
circuit is open.

3. If battery condition meter and run lamp

3. Replace time meter.

works but time meter does not operate,
time meter is defective.

4. If time meter works but battery condition
meter does not operate, connect a
voltmeter between the positive terminal
on battery charge meter and ground.
Use the following to determine fault
a. If reading equals battery voltage
minus 10 volts, battery condition
meter is defective.
b. If reading does not equal battery
voltage minus 10 volts, zener diode is
defective.

7-8

4a. Replace battery condition meter.
b. Replace zener diode.

Redistribution or publication of this document
by any means, is strictly prohibited.

Many troubleshooting procedures present hazards which can result in severe personal injury or
death. Only qualified service personnel with knowledge of fuels, electricity, and machinery hazards
should perform service procedures. Review safety precautions on inside cover page.

Trouble

Corrective Action

Possible Cause

s

5. Meters and switch function properly but
run lamp does not illuminate. Lamp
(internal to switch) is burned out.

5. Replace remote start-stop switch S2.

6. Remote switch functions properly
(starting and stopping generator set) but
meters and run lamp do not operate.
Current sensing resistor R4 on control
board A i has opened, caused by a
short in the remote control wiring
between control board P2/J2 terminal
6 / 5 and remote control time meter, run
lamplbattery condition meter.

6. Check for continuity of remote wiring
harness and wiring on remote control in
series with terminals 6 and 5. Replace
wiring of shorted circuit.

Generator Set
Does Not Stop
After Switch is
Pushed to Off
Position

1. Faulty set control start/stop switch (Sl)

1. Check start/stop switch and replace
if defective.

Note: Always
remove load
a few minutes
before stopping
to allow set to
cool down.

3. Defective K3 relay.

REMOTE
CONTROL
(if equipped)
Run Lamp, Time
Meter, or Battery
Condition Meter
Does Not Operate
(Continued)

2a. Check for continuity and correct if circuit
2. **K5 relay not energizing
is open
(its N.O. contacts should be open) due tc
b. Replace K5 relay.
a. Open circuit to K5 relay coil
b. Faulty K5 relay.
3.

Replace control circuit board.

**LPG Sets Only.

7-9

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by any means, is strictly prohibited.

Section 8. Generator
GENERATORKONTROL

*

The inner end ofthe rotor is connecteddirectly tothe engine
crankshaft using a tapered seatishaft coupling and
through-bolt The outer end of the rotor is supported by a
single bearing that is pressed onto the rotor shaft The
bearing fits inside the generator housing.

COMPONENTDESCRIPTIONS
The generator and its control components consist of the
following: (Refer to Figure 8-1.)
0
0

0
0
0
0
0
0

Control Printed Circuit Board (Al)"
Brushes
Rotor
Stator and Housing
Terminal Board (TB1)
Voltage Regulator (VR1)
Circuit Breaker(s) (CB1, and CB2 if equipped)
Wiring Harness to Load(s)

Coolingairflow for the generatoris providedby a centrifugal
fan that mounts on the inner end of the rotor shaft. The fan
also serves as a mount for the starter ring gear.

Stator and Housing
During generator set operation, AC current is produced in
the windings of the stator. All stator winding leads are routed
into the generator set control housing compartment, for
control component connection as follows:

*Refer to Section 7, Control, for further information.

0

Control Printed Circuit Board (Al)
Initialexcitation voltage to the generator rotor is supplied by
the generator set starting battery BT1. During cranking of
the engine, DC voltage of the battery is supplied through
N.C. contacts of generator relay K2 (on control board Al),
through the voltage regulator VRl , to the brushes and slip
ringsof the rotor. Upon successfulenginestart andgenerator voltage build-up, generator relay K2 becomes energized, which 0penstheN.C. contacts inthe battery B+ circuit
to the voltage regulator and closesa set of N.O. contacts in
the start disconnect/run relay K3 circuit of board Al. This
circuit keeps relay K3 energized while the set is in operation.
If relay K2 becomes de-energized, the set will shut down.

0
0

Leads T1, T2, T3, and 14 to Terminal Board TB1, for
supplying power to load.
Leads B1 and B2 to Control Board All wiring harness
J1, for supplying power to generator relay K2.
Leads Q1 and Q2 to Voltage Regulator VR1, wiring
harness J4, for excitation voltage of rotor. (AC voltage
from stator is rectified to DC voltage in VRI.)

The stator mounts inside the generator housingand is held
in positionwith clamps and capscrews. A seriesof air intake
openings in the end of the housing allow cool air to be
drawn insidethe housingfor generator cooling. The housing also provides a mounting point for the engine starter,
rear rotor bearing, exciter brush block, controlcomponents,
and fuel pump or solenoid (LPG). The complete stator and
housingassembly boltsto the engine-to-generatoradapter.

Brushes
DC excitation voltage is induced through the brushes and
rotor slip rings to the rotor windings. The brush block
assembly consists of asingle brush block with two brushes.
The brush block mounts inside the generator housing,
directly over the rotor slip rings, and can be accessed by
removing the small plate at the rear of the housing.

Terminal Board (TBl)
The AC output power leads from the generator (Tl, T2, T3,
and T4) are connected to terminal board TBl at terminals
L1-LO (connection configuration is model dependent, refer
to proper Wiring Diagram/Schematic for further information). AC powerat TBl terminalsistappedby leadsof wiring
harness J4 of voltage regulator VRl, and interconnectwiring to the circuit breaker(s) CB1 (and CB2, if equipped).
These leads providegenerator outputto the voltage regulator for propervoltage regulation,andtothe circuit breaker(s)
for power supply to load.

Rotor
The 4-pole rotor providesthe rotating magneticfield that is
requiredfor generating an AC voltage potential in the stator
windings. The DC current required for field excitation is
supplied through twoslip ringsthat mount on the rotor shaft
9

8-1

Redistribution or publication of this document
by any means, is strictly prohibited.

Voltage Regulator (VR1)
The voltage regulator helps to provide stable generator
output voltage under varying load conditions. During
initial start of the generator set, the voltage regulator
receives DC current from the set starting battery, and
begins excitation of the rotor (through leads J4-9/F1,
and J4-1 O/F2). After the generator set starts and runs, it
provides AC power to the voltage regulator (through
leadsJ4-11 /Q1, and J4-12/Q2). The AC voltage is rectified to DC voltage, and the proper DCexcitation voltage
is induced to the rotor in response to changes in load
demand.
The voltage regulator design reduces the risk of component failure by not allowing moistureto contact/interfere with its operation, by; the printed circuit board control being encased in the regulator housing with a
potting compound, the booted ends of the J4 wiring
harnesscoveringthe terminalsof capacitor C5 (mounted
to the outside of the regulator housing), and the wiring
harness plug-in P4 being treated with a lubricant prior
to connection. Further protectionis provided by mounting the voltage regulator assembly inside the generator
control housing.

Control Circuit Breaker(s)
(CB1, and CB2 if equipped)
The output power from the generator set is supplied to
the control circuit breaker(s), located on side of the
control right housing. The ampere rating of the circuit
breaker@) may differ, depending on generator set
model/frequency. Be sure to refer to proper Parts Manual when ordering any replacement parts.

Wiring Harness to Load@)
A separate wiring harness is provided for connecting
the generator set to the RV electrical system. All lead
wires are stranded copper wire to withstand vibration.
The lead wires must be protected with flexible conduit
from the generator set control housing to the RV switching/disconnect device, which must be provided by
the RV manufacturer. The lead wires exit the control
housing behind the fuel pump/solenoid. The load conductors are black, the neutralconductorsare white, and
the ground conductor is green.

When the start-stop switch is placed in the STARTposition, the rotating field (rotor) is momentarily connected
to battery positive (B+) to provide adequate residual
magnetism for voltage build-up. As the engine starts
and speed increases,the rotating field induces avoltage
build-up in the stator windings. A portion of the AC
current generated in the stator windings is provided to
the voltage regulator (VR1) by the quadrature windings
(01,(22). The ACvoltage is rectifiedto DC by the voltage
regulator.The DC current is suppliedto the rotating field
windings to create the strong magnetic field required for
generating the rated current. The AC voltage build-up
stabilizes at approximately 128 volts when the engine
reaches governed speed.
To prevent an excessive voltage drop when a load is
applied to the generator, a methodfor regulating the AC
output voltage is required. The voltage regulator allows
the generator to provide a stable AC output voltage
under varying load conditions through wire taps from
voltage regulatorVR1wire harnessJ4-2 and -3 that are
connected to terminal board TB1. These leads sense
voltage changes of the load on the generator.
During operation, adding load increases the current
flow through terminal board TB1 and the sensing leads
to the regulator. The circuitry of the voltage regulator
will then adjust the DC excitation voltage to the rotating
field to a higher level, offsetting the voltage drop that
would normally occur when a load is applied. In the
same manner, decreasing the load reduces the DC field
current to offset the voltage rise that would normally
occur when a load is removed. Continuously adjusting
the field current as the load changes is how voltage
regulation is achieved.
Efficientgenerator set performance relieson effectivevoltage regulation and maintaining proper frequency
(engine speed). Load changes on the generator output
can cause engine speed to decrease or increase significantly. If the governor does not maintain proper engine
speed, too much of a burden can be imposed on the
voltage regulator to provide proper current to load.
Review the information in Section 6, Engine Primary
Systemsfor governor troubleshooting and adjustments.

GENERATOR OPERATION
Generator operation involves all control components
previously described. The wiring diagrams/schematics
examples shown in Figures8-2,8-3,8-4, and 8-5 reflect
representative generator set models, and are intended
for reference only. Always refer to the specific wiring
diagram/schematic that corresponds to the specific
generator set when troubleshooting problems.

8-2

P

Redistribution or publication of this document
by any means, is strictly prohibited.

GENERATOR
HOUSING

I

\

STATOR
STATOR
CLAMPS

ROTOR
END-BEARING

\

ROTOR
6-1212

ENGINE-TO-GENERATOR
ADAPTER HOUSING

FIGURE 8-1. GENERATOR CONTROL COMPONENTS

8-3

Redistribution or publication of this document
by any means, is strictly prohibited.

DELUXE

- -

LOAD

NEUTRAL f

- IZOV

-+

REMOTE PANELS
STANDARD

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RESISTOR-FUEL P U M P
IOLTAG E REGULATOR
IGN POINTS
SWITCH-LOW OIL PRESSURE
RESISTOR BATTERY CHARGE

WIRING DIAGRAM

-

RELAY- START

SOLENOID

CHOKE
GENERATOR
FUSE

J

SPARK PLUG
FUEL PUMP
IGN COIL
CIRCUIT B R E A K E R I A C OUTPUT1
CAPACITOR
BATTERY 12V
STARTER MOTOR
REMOTE CONTROL-STANDARD
REMOTE CONTROL- DELUXE
CONTROL ASSY- HHE/NHF.L
CONTROL ASSY- E G E / B G E L

611-1 180

D.scwlm w U.I.IUI

FIGURE 8-2. 60 HZ BGE/NHE GASOLINE-FUELED GENERATOR SET WIRING DlAGRAMlSCHEMATIC
(Prior to Spec G: Breaker Points and Condenser)

8-4

Redistribution or publication of this document
by any means, is strictly prohibited.

REMOTE PANELS
DELUXE

STANDARD

I

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GND

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-. JUMPER - S E E NOTE 2
RECTIFIER- F U E L PUMP
RESISTOR-BATTERY CHARGE
V O L T A G E REGULATOR
IGN POINTS
SWITCH-LOW OIL P R E S S U R E
POTENTIOMETER
RESISTOR - F U E L
PUMP

RS
R7
RECONNECTION CHARTS

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CAPACITOR

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RATT E RY 12V
STARTER MOTOR

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GROUNDEDAC LEAD - FOR ISOLATEDNEUTRAL, REMOVEJUMPER (W2TB1 L3 LO AND
CONNECT JUMPER m - L o . 3mc~
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FIGURE 8-3. 50 HZ BGElNHE (GASOLINE-FUELED)GENERATOR SET WIRING DlAGRAMlSCHEMATlC
(Prior to Spec G: Breaker Points and Condenser)

8-5

Redistribution or publication of this document
by any means, is strictly prohibited.

A2

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DESCRIPTIONOF MATERIAL

1 VOLTAGE REGULATOR

51
53

IGN COIL
IGN MODULE
SWITCH-LOW OIL PRESS
RESISTOR-BATTERY CHARGE

52
R6
R5

POTFNTIOMFGR

K5
K1

REMY-START SOLENOID

RELAY-LPG ONLY

H1

CHOKE-GASOLINE ONLY

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REMOTE CONTROL-STANDARD
REMOTE CONTROL-DELUXE
CONTRO-ASSY-NhEINHEL
CONTROLASSY-EGEIBGU

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61 I - I I90
FIGURE 8-4. 60 HZ BGEINHE GENERATOR SET WIRING DlAGRAMlSCHEMATlC
(Spec G Electronic Ignition)

8-6

Redistribution or publication of this document
by any means, is strictly prohibited.

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I
I

II
I

I

C31

.

TI LI

I
T3 L2

I
A

2201240V

I

I

611-1191
FIGURE 8-5. 50 HZ BGElNHE GENERATOR SET WIRING DIAGRAM/SCHEMATIC
(Spec G: Electronic Ignition)

8-7

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by any means, is strictly prohibited.

GENERATOR TROUBLESHOOTING

8-5 for the location of all terminal connections. The
troubleshooting guide is divided into sections. After
identifying the problem, refer to the guide for the POssible cause and the recommended corrective
action.

Use the following troubleshooting guide to help locate
problems relatedtothe generator. Figure 8-1 shows the
location of the generator components. Refer to the wiring diagrams/schematics in Figures 8-2, 8-3, 8-4, or

TROUBLESHOOTINGTHE GENERATOR
Many troubleshoofingprocedures present hazards which can resulf in severe personal injury or
laWAR"Gl
death. Only qualifiedservicepersonnel with knowledge of fuels, electricity, and machinery hazards
should perform service procedures. Review safety precautions on inside cover page.
Trouble

No AC Output
Voltage
Note: This condition
may cause the
generator set to
stop when start
switch S1 is
released.

AC Output Voltage
Too Low or Too
High

Possible Cause

I

Corrective Action

1. Open circuit breaker.

1. Locate cause of overload and correct

as required. Reset breaker.
2. Open circuit between voltage
regulator and brush block.

2. Check for good wiring connections
and correct as required. Check for
continuity and correct if circuit is open.

3. Open circuit between generator windings (Ql, Q2) and voltage regulator.

3. Check for good wiring connections
and correct as required. Check for
continuity and correct if circuit is open.

4. Open circuit between terminal block
TBl and voltage regulator; wiring
harness J4 leads.

4. Check for good wiring connections
and correct as required. Check for
continuity and correct if circuit is open.

5. Brushes stuck in holder or not making
good contact with slip rings.

5. Release brushes if jammed in holder.
Clean slip rings if dirty.

6. Defective voltage regulator.

6. Replace voltage regulator.

7. Open, grounded, or short circuit in
rotor or stator.

7. Test each component for open,
grounded, or shorted windings and
replace if defective.

1. Engine governor incorrectly adjusted.

1. Refer to governor adjustments in
section 6.

2. Brushes worn or not making good
contact with slip rings. (Low AC
output voltage.)

2. Check length of brushes and replace
if worn excessively. Clean or replace
slip rings.

3. Poor wiring connections to/from
voltage regulator.

3. Check for good wiring connections
and correct as required. Check for
continuity and correct if circuit is open.

4. If generator frequency is within

4. Refer to Testing Voltage
Regulator VRI.

specified limits but voltage is incorrect,
voltage regulator is defective.
5. Open, grounded, or short circuit in
rotor or stator.

5. Test each component for open,
grounded, or shorted windings and
replace if defective.

6. Voltage Regulator sensing leads
2 and 3 wired incorrectly.

6. Correct wiring.

8-8

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by any means, is strictly prohibited.

TROUBLESHOOTING T H E GENERATOR (Continued)

k@k%l

Many troubleshooting procedures present hazards which can result in severe personal injury or
death. Only qualifiedservice personnel with knowledgeof fuels, electricity, andmachineryhazards
should perform service procedures. Review safety precautions on inside cover page.
Trouble

Corrective Action

Possible Cause

9

*

Noisy Generator

1. Loose brush holder.

1. Tighten brush holder

2. Worn generator end bearing.

2. Replace end bearing.

3. Rotor and stator rubbing together

3a. Check for varnish lumps between
rotor and stator, remove as required.
b. Follow specified assembly procedures
to correct rotor to crankshaft
alignment.

due to:
a. Varnish lumps.
b. Rotor misaligned with crankshaft.
Generator
Overheats

1. Generator overloaded due to
defective circuit breaker.

1. Remove part of load and replace
circuit breaker.

2. Airflow restricted due to dirt or
debris covering vent openings in
stator housing.

2. Clear away all dirt or debris as required.

3. Stator windings covered with oil
or dirt.

3. Clean stator windings.

4. Open, grounded, or short circuit in
rotor or stator.

4. Test each component for open,
grounded, or shorted windings and
replace if defective.

5. Defective voltage regulator.

5. Refer to Testing Voltage Regulator VRI.

8-9

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GENERATOR SERVICE
This section covers generator disassemblyand assembly procedures. Refer to Figure 8-1 to locateand identify
the various generator components described, and Figure 8-2, 8-3, 8-4, or 8-5 for wiring interconnect
information.

Generator Disassembly
Use the following procedure to disassemble the
generator:
1. Drain the engine oil while the generator set is still
mounted in the vehicle.
2. Remove the generator set from the vehicle and
place it on a sturdy work bench. Referto Set Removal in section 5 for the recommended set removal
procedure.
3. Remove the flywheel guard (from scroll opening)
and the sound shield.

HOLE
6-1178

FIGURE 8-6. BRUSH BLOCK ASSEMBLY

4. The carburetor and intake manifold must be
removedto provide clearancefor liftingthe generator stator assembly. Disconnect the choke heater
lead wires, throttle linkage, fuel line crankcase
breather hose, and preheater tube. Remove the
intake manifold screws and lift off the carburetor
and intake manifold as an assembly. Refer to Fuel
System in section 6for detailed removal procedure.

5. Disconnectthe lead wires from the charge resistor,
low oil pressure cutoff switch, and B+ terminal on
the ignition coil.
6. Remove the brush block cover and disconnect the
F1 (+)(outboard)and F2 (-) (inboard)lead wiresfrom
the brush block terminals.

7. Pull each brush lead wire outward from the holder
and at the same time insert a piece of stiff wire into
the small hole in the end of the stator housing,'see
Figure 8-6. Carefully guide the wire through the
brush block and then releaseeach brush.Verify that
each brush is held off the slip rings by the holding
wire.

8. Removethe two control panel screws from housing,
lift off control panel and disconnect plug/jack connections P1/J1 and P3/J3 of control printed circuit
board.
9. If the set is LP-gas fueled, disconnect the fuel line at
the vaporizer coupling.
10. Place a 3/8 inch allen wrench in the head of the
rotor through-bolt. Use a rubber mallet and sharply
strike theallen wrench so the through-bolt is driven
in a counterclockwise (viewed from generator end)
direction. Several sharp tapsshould break loosethe
through-bolt.
11. Remove the rotor through-bolt and thread the special liftingeye(9/16-12)into theendofthe housing.
Refer to Figure 8-7.

The brushes will be damaged
during disassembly if not held
off the slip rings. Make certain holding wire is in
place before removing stator assembly.

/

01176-2

FIGURE 8-7. GENERATOR LIFT

8-10

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by any means, is strictly prohibited.

12. Place a pad in front of the engine to cushion and
protect the scroll. Attach a hoist or other suitable
lifting device to the lifting eye. Tip up the set as
shown in Figure 8-7 until it is completely vertical
and resting on the scroll housing end.

7)

v

.

Careless handling can damage
the rotor. Do not lift the entire
generator set by this method.
13. Remove the capscrew and two EIT lock washers

that secure the ground strap to the drip pan.

ACAUT~ON Careless handling of the stator

assembly can damage the insulation on the stator windings. Do not brush the
stator windings againstthe rotor as it is liftedclear.

19. Install the tool shown in Figure 8-9. Use a screwdriver to turn the rotor tool in a clockwise direction
until it bottoms. Installa 9116-12 x 2 capscrew in the
end of the rotor shait and tighten until rotor breaks
loose from crankshaft. Remove capscrew from end
of rotor when complete.

14. Remove the three vibration isolator center screws
from the underside of the drip pan and lift drip pan
away from engine-generator.
15. Disconnectlead wiresattached to thestarter motor.

Loosen the fasteners that mount the starter to the
stator housing, and remove starter.
16. Removethefourcapscrews, lock washers, and nuts
that secure the stator housing to the engine-togenerator adapter.

17. Remove the lifting eye bolt (Figure 8-8).

18.Carefully lift the stator assembly straight up until it
clears the rotor. Set stator assembly to rest on
smooth, clean surface.

/

ROTOR TOOL
10 IN. (254 rnm)
(7/16-14)

6-1175

FIGURE 8-9. ROTOR TOOL

20. Carefully lift the rotor assembly off the end of the
engine crankshaft and remove rotor tool.
21. Lift the brush wires and remove brush holding wire
from housing. Remove the brush block mounting
screw and carefully remove the brush block
assembly from the stator housing.

61175.1

FIGURE 8-8. REMOVE LIFTING EYE BOLT

8-11

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by any means, is strictly prohibited.

22. Refer to Figure 8-10 and use the following procedure to remove the stator from the stator housing:

a. Rotate the stator/housing assembly onto a
smooth, clean surface, resting on end-bearing
face (bell shape of housing facing up).
b. Disconnect stator leads;
T1, T2, T3, and T4 from terminal board TB1,
Q1 and Q2 from voltage regulator VR1 harness J4,
B1 and 82 from control printed circuit board
harness J1.
c. Draw stator leads from control box.
d. Remove the three stator clamps and capscrews.
e. Carefully lift the stator straight up until it clears
the stator housing.Set stator to rest on asmooth,
clean surface.

EM4951
61175

FIGURE 8-loa. BEARING REMOVAL

Carelesshandling of the sfafor can damage the insulation on the stator windings. Do not brush fhe
windings against the housing as it is lifted
clear, and take care not to drop or drag the
sfator on work area outside of stator housing.

1-

Bearing Replacement
1. Clean the bearing and shaft mating surfaces.
2. Apply Loctite #680 adhesive to the shaft mating
surface.
3. Apply Loctite #747 activator to the bearing mating
surface.
4. Install the bearing and allow ten minutes curing
time before handling the assembly.

Component Inspection
While the generator components are disassembled,
perform rotor and stator tests as indicated in Generator
Testing, this section. Also check mechanical condition
of generator parts (rotor end-bearing, generator housing and O-ring, etc.) for signs of wear. Refer to proper
unit Parts Manualand replaceany components found to
be defective.

Generator Assembly
Use the following procedure to assemble the generator:
1. Refer to Figure 8-10 and use the following procedure to install the stator into the stator housing:
6-1213

a. Position the stator so the output leadsalign with
access hole to control housing, then carefully
lower the stator straight down into the stator
housing.

FIGURE 8-10. STATORlHOUSlNG DISASSEMBLY

Rotor Bearing Removal

of
@
%
!
!
@
I
on
Do
brush

Careless handling the stator can damage the insulation
the stator windings.
not
the
windings against the housing as it is lowered
into housing, and take care not to drop or drag
the sfafor on work area outside of sfator
housing.

Use a gear puller to remove the bearing from the rotor
shaft. Attach the gear puller so that the gear puller arms
contact the inner race of the bearing (Figure 1).
The bearing will be damaged if
pulled by the outer race. If the
bearing is to be reused, it must be pulled by the
inner race.

8-12

I

#

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by any means, is strictly prohibited.

10. Secure ground strap to drip tray using a capscrew

b. Install the three stator clamps and capscrews.
c. Draw stator leads into control box.
d. Connect stator leads;
T1, T2, T3, and T4 to terminal board TB1,
Q1 and Q2 to voltage regulator VR1 harness

and two EIT locking washers. Note that ground
strap is installed between locking washers to provide a good electrical connection.
11, Attach the special lifting plateto the end of the stator
housing using four 5/16-18 x 1 capscrews. See
Figure 8-7.
12. Attach a hoist or other suitable lifting device to the
lifting plate. Carefully tilt the set back until it is resting on the drip tray. Remove lifting plate when
complete.
13. If the set is LP-gas fueled, connect the fuel line at the
vaporizer coupling.

J4.
0

B1 and B2 to control printed circuit board
harness J1.

e. Rotate the stator/housing assembly onto a
smooth clean surface, resting on bell shape of
Iiousing (end-bearing face up).

-

2. Install the brush block assembly into the stator
housing. Lift the brush wiyes and install brush holding wire into housing.The wire holds the brushes off
the slip rings during assembly. See Figure 8-6.
3. Carefully place the rotor assembly onto the end of
the engine crankshaft and replace the rotor
through-bolt. Tighten rotor through-bolt only
enough to hold rotor in place.
Tightening the rotor throughbolt to specified torque before
the stator assembly is installed can result in rotor
shaff misalignment. Follow recommendedinstallation procedures to avoid any possiblity of shaft
misalignment.

4. Carefully place the stator assembly straight down
over the rotor and into position for assembly to the
engine-to-generatoradapter. The rotor end-bearing
should fit snugly into the bearing hole.
Careless handling of the stator
assembly can damage fhe insulation on fhe sfator windings. Do not brush the
stator windings against the rotor as it is lowered
into position.
5. Install the four capscrews, lock washers, and nuts
that secure the stator housing to the engine-togenerator adapter. Tighten capscrews to specified
torque. Note that each locking washer is installed
under capscrew head.
6. Tighten the rotor through-bolt to specified torque.
7. Mount starter on generator stator housing using
capscrews, lock washers and nuts. Tighten to specified torque.
8. Connect lead wires to starter terminal stud.
9. Hold the drip pan in position for mounting to the
underside of the set and install the three vibration
isolator center screws. Note that properflat washers
are used (large flat washers at two generator isolator positions). Tighten the center screws to specified torque.

14. Connect plugljack connections P l / J l and P3/J3

of control printed circuit board. Install control panel
assembly onto generator housing. Tighten mounting screws.
15. Pull the brush lead wires outward and remove the
piece of wire that is holding the brushes off the slip
rings. Check the brushesto verify that they are centered on the slip rings. If brushes are not centered,
loosen the brush block mounting screws and adjust.
Retighten mounting screws when complete.
16. Connect the F1 (+) (outboard) and F2 (-) (inboard)
lead wires to the brush block terminals. Install the
brush block cover.
17. Connect the lead wires to the charge resistor, low oil
pressure cutoff switch, and B+ terminal on the ignition coil.
18. Place new intake manifold gaskets on the engine
block and installthe carburetor and intake manifold
assembly. Tighten the intake manifoldscrewsto the
specified torque. Connect the preheater tube,
crankcase breather hose, fuel lines,throttle linkage,
and choke heater wires. Refer to Fuel System in
section 6 for detailed assembly procedures.
19. Install the flywheel guard (scroll opening) and the
noise shield.
20. Install the generator set in the vehicle and securely
fasten all mounting screws and hardware. Connect
the fuel, exhaust, and electrical system in reverse
order of disassembly. Refer to Set Removal in section 5 for the recommended procedures.
21. Fill crankcasewith oil of the recommendedclassifi.
cation and viscosity.

8-13

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by any means, is strictly prohibited.

BRUSHES AND SLIP RINGS
Brush Replacement

7. Pull and hold both brush lead wires outward from

Remove the brush block cover and inspect the brushes
and brush holder for burn marks or other damage. If the
brushes appear to be in good condition, use a piece of
wire (modified as shown in Figure 8-11) to check for
excessive brush wear. Insert the wire through the hole
above each brush. Make sure the wire is resting on the
brush and not on part of the spring. If the painted part of
the wire is not visible, the brush is excessively worn and
must be replaced.

8. While continuing to hold brushes away from slip
rings, insert brush retainer wire from outside stator
housing hole, through brush block assembly.
Release both brush lead wires. See Figure 8-1 2.

brush holder. Place brush block assembly into
mounting position inside stator housing.

n
BRUSH
BLOCK

A

-

-T
SPRING

6.1174

-

FIGURE 8-11. CHECKING BRUSH WEAR

Always replace the brush springs when installing new
brushes so that proper pressure is maintained when
brushes contact slip rings.

SECTION A-A

BRUSH

G-1179

FIGURE 8-12. BRUSH REPLACEMENT

Use the following procedure to replace the brushes.
1. Disconnect the negative (-) battery cable at the battery terminal.

9. Install brush block mounting screws and tighten
only enough to hold brush block assembly in
position.

2. Remove the air cleaner cover and air cleaner filter
element.

10. Lift both brush lead wires and remove brush retaining wire completely from stator housing.

3. Remove the brush block cover from stator housing.

11. Adjust brush block assembly so that brushes are

4. Disconnectthe F1 (+) (outboard)and F2 (-) (inboard)

voltage regulator lead wires from the brush block
terminals.
5. Remove the brush block mounting screws and lift
out the brush block.
6. Removebrushesand brush springs from holder and

replace with new parts.

aligned on slip rings, and tighten brush block
mounting screws.
12. Connect the voltage regulator and brush lead wires
to brush block terminals; F1 with (+)outboard brush
lead, and F2 with (-) inboard brush lead.

L

13. Install brush block cover onto stator housing.

14. Install air filter element and air cleaner cover.
15. Connect negative (-) battery cable to battery
terminal.

8-14

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by any means, is strictly prohibited.

Slip Ring Service
Removethe brush block cover and inspecttheslip rings
for grooves, pitsor other damage. If theslip rings are not
in good condition, they may be refinished using a commutator stone. Use the following procedureto service:

1. Remove the air cleaner cover and air cleaner filter.

to the first terminal of each pair. Replacethe voltage
regulator if any reading indicates“short” or “open“,
except for pair 10-5, which should indicate “open”.
“Short” is indicated by zero or a number very nearly zero.
Meters of different make indicate “open” differently. Read the
meter instructions. If in doubt, comparewith readingsof a regulator of the same part number known to be good.

2. Discconnect voltage regulator lead wires F1 and F2
from the brush block terminals and then insulatethe
lead wire ends. Tie the lead wires to one side to
allow clear access to the slip rings.

3. Remove the brush block mounting screws and lift
out the brush block assembly.

4. Insert a 3/8 inch allen wrench into rotor throughbolt and rotate engine and generator one full turn.
While rotating, inspect condition of slip rings. If slip
rings require refinishing, continueto next step. If slip
rings do not require refinishing, follow steps 6
through 14 in the Brush Replacement section.
I

1

5. Press the Start-Stop switch to START position to
crank the engine. During this step, only crank the
engine for 3to 6 second cranking periods with a rest
period between so not to overheat starter.

During engine cranking, hold a commutator stone
against rotating slip rings. Remove commutator
stone after each cranking period and check that
carbon is being removed and all grooves or roughness is smoothed out.

I
AWARNING

Contact wifh rotating machinery
can result in severe personal

ES-1952C

FIGURE 8-13. VOLTAGE REGULATOR CONNECTOR
TERMINALS

GENERATOR TESTING
This section covers the test procedures for the generator rotor and stator windings. Follow the troubleshooting procedures in this section to locate the required
corrective action.

injury. Keep hands and fingers clear while servicing slip rings.

Perform the Field Voltage Test to confirm that field voltage is availableto the rotor brushesthrough the voltage
regulator for field flashing and voltage buildup.

6. Remove insulating material from ends of voltage
regulator lead wires F1 and F2, and then install
brush block assembly. Follow steps 6 through 14 in
the Brush Replacementsection.

Check all wire harness connectors and leads for continuity prior to
testing or generator disassembly. Refer to Figure 8-1 for wire
locations.

Field Voltage Test

TESTING VOLTAGE REGULATOR VR1
Confirm that voltage regulator VR1 is faulty before
replacing it. Usea meter with a diode checking function
(Fluke Model 73 Multimeter) to perform the following
tests.

1. Disconnect the negative (-) battery cable.
6

2. Remove the generator control box cover (Figure

8-1).
*

A voltage check can be made to determine if voltage is
being suppliedto the brushesfrom thevoltage regulator
for voltage buildup.

Connect a DC voltmeter positive (+) test lead into the
voltage regulator plug (Pl)at pin 9 and connect the
negative (-) test lead into the voltage regulator plug at
pin 10.Thevoltage regulator plug remainsconnectedto
the voltage regulator and test leads should be secured
so they are not being held during testing. See Figure

8-13.

3. Disengage the wiring connector and remove the

voltage regulator.

Electrical shock can cause severe
laWAR”Gl
personalinjury or death. Use extreme
caution when working on electrical circuitry. Affach

4. With the meter on “Diode Check”, test between
and remove meter leads only whengenerator set is nof
connector terminal pairs 5-9,7-9,lO-9,ll-9,12-9,
operating. Do not touch meter or meter leads during
10-5,5-11,5-12and 5-3(Figure 8-13).It is importesting.
tant that the positive lead of the meter be connected

8-15

Redistribution or publication of this document
by any means, is strictly prohibited.

@&@@I
clothing,
hands,
ing slip rings.

Contact with rotating machinery can
result in severepersonal injury. Keep
jewelry and fingers clear while servic-

Start the generator set and allow it to stabilize. Measure
the field voltage with no load applied and then with full
load applied. Both readings should fall within a range of
18to60 volts DC. If the set cranks but will not run, check
to see that battery voltage is being supplied to the voltage regulator pin 7 (positive lead) and ground (negative
lead) during start up. If battery voltage (approximately 12
volts) is being supplied to the voltage regulator at pin 7,
and no output voltage was measured, check thevoltage
at the brushes. If the voltage is zero, replace the voltage
regulator and retest. If battery voltage is not supplied to
the voltage regulator during starting, refer to Control
section (7) for troubleshooting procedures.

Rotor Tests
The rotor can be tested for grounded, open, or shorted
windings using an ohmmeter. Figures 8-14 and 8-15
show the rotor removed from the generator for testing.
However, it is possibleto test the rotor without removing
it from the generator. To obtain access to the slip rings,
remove the brush block cover. Lift the brush lead wires
and insert a brush retaining wire from outside stator
housing, through brush block assembly to hold the
brushes of the slip rings during testing.

4

1

Ground Test: To test for grounds, set the ohmmeter for
the highest resistance scale. Touch one test lead to the
rotor shaft and hold it there. Touch the other test lead to
one of the slip rings. See Figure 8-14. A reading less
than one megohm indicates the rotor is grounded.
Replace a grounded rotor with a new rotor.

ES-1558-1

FIGURE 8-14. TESTING ROTOR FOR GROUNDS

8-16

Redistribution or publication of this document
by any means, is strictly prohibited.

Open or Shorted Windings Test:To test for open windings, set the ohmmeter for the highest resistancescale.
Place test leads on the slip rings as shown in Figure
8-1 5. Ohmmetershouldindicatecontinuitybetween slip
rings. A high resistance reading indicates a poor connection or an open winding. Check the connection
between the slip rings and rotor lead wires. Replace
rotor if the rotor winding is open.

Stator Tests
The stator can be tested for grounded or open windings
using an ohmmeter. Testing for shorted windings
requires a digital-type ohmmeter that can read to within
0.01 ohms.

Figures 8-16 and 8-1 7 show the stator removedfrom the
generator for testing. However, it is possible to test the
stator without disassemblingthe generator. Removethe
control panel to obtain access to the specified lead
wires during testing.

b

.
l

To test for shorted windings, set the ohmmeter for the
lowest scale. Place the test leads on the slip rings as
shown in Figure 8-15. Resistance reading should be
20.25 to 24.75 ohms at 77' F (25" C).Replace a rotor
with shorted windings with a new rotor.

Ground Test:To test for grounds, disconnectthe following stator leads:
0
0
0

Stator leads T1 and T 3 from TB1
Stator lead B1 from A1 /P1-1
Stator lead Q1 from VR1 /J4-11

Insulate or position the lead wire ends so they are not
touching the generator set housing or other components within control. Set the ohmmeter for the highest
resistance scale and then connect one test lead to the
generator housing. Touch the other test lead (see Figure
8-16) to the listed generator leads individually. A reading less than one megohm indicates a ground. Replace
a grounded stator with a new stator.

ES-1558-2

FIGURE 8-15. TESTING ROTOR FOR OPENS OR SHORTS

TEST LEADS
T1. T3. B1 and Q1

FOR GROUNDS
6-1214

FIGURE 8-16. TESTING STATOR FOR GROUNDS

8-17

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by any means, is strictly prohibited.

Open or Shorted Windings Test: To test for opens,
disconnect stator leads; TI, T2, T3, and T4from TBl, B1
and B2 from Al, and Q1 and Q2 from VR1. Set the
ohmmeter for the highest resistance scale and then
connect the test leads (see Figure 8-16) to the generator
lead ends in pairs: T1/T2, T3/T4, B1/B2, and Q1 /Q2.
The ohmmeter should indicate continuity between lead
ends. A high resistance reading indicates an open winding. Replace an open stator with a new stator.

n

To test for shorted windings, use a digital-type ohmmeter that readsto within 0.01 ohms. Disconnectthe stator
leads as specified in Open Test section. Connect the
test leads (see Figure 8-17) to the leads in pairs as
specified in the Open Test section. The readingfor lead
pairs should be as follows (plus or minus 10 %):
60 Hz Models
Leads T1 /T2 - 0.327 ohms
Leads T3/T4 - 0.327 ohms
Leads B1/B2 - 0.058 ohms
Leads Q1/Q2 - 2.089 ohms

TEST LEADS:
T3/T4, E1 IB2, and 01I02

6-1214-1

50 Hz Models

Leads T1 /T2 - 0.502 ohms
Leads T3/T4 - 0.502 ohms
Leads B1/B2 - 0.1 12 ohms
Leads Q1 /Q2 - 2.873 ohms

FIGURE 8-17. TESTING STATOR FOR OPENS OR SHORTS

A reading lessthan thesevaluesindicatesshortedwindings. Replace a shorted stator with a new stator.

8-18

Redistribution or publication of this document
by any means, is strictly prohibited.

Section 9. Engine = Block Assembly
V

I

GENERAL

CYLINDER HEADS

The engine block assembly includes the pistons and
connecting rods, crankshaft, camshaft, valves and lifters, cylinder heads, lubrication system, timing gears,
governor mechanism, bearings,and cylinder block. Performing any major service on the block assembly will
require that the generator set be removed from the
coach (see Set Removal section). In addition, to gain
complete access to the block assembly, the control,
generator, and all primary engine systems must also be
removed. Refer to the previous sections for the disassembly and removal procedures.

Remove the cylinder heads for cleaning when poor
engine performance is noticed. Use the following
procedures to service.

OIL FILTER AND ADAPTER
Open the oil drain valve and drain the crankcase oil.
Remove the filter (see Figure 9-1) by turning counterclockwise with a filter wrench. The low oil pressure
cut-off switch is installed in a threaded hole in the filter
adapter and may be removed if required. Loosenthe two
capscrews that secure the adapter to the engine block
and remove the adapter and gasket.
Assembly is the reverse of disassembly. Use a new
adapter gasket and install so the two small oil holes are
aligned with theoil holes in the block. Gasket should be
installed dry. Coat the threads of each capscrew with
non-hardening sealer and tighten to recommended
torque.

1. Use a socket wrench to remove the cylinder head
capscrews, and lift off the head.

Warpage can occur
@@
%!I

if the heads
are removed while hot. Waif until
engine has cooled before removing heads.

2. After removing heads, clean outall carbon deposits.
Be careful not to damage the outer sealing edges
where gasketsfit. The heads are made of aluminum
and can be damaged by careless handling.
3. Use new head gaskets and clean both the heads
and the cylinder block thoroughly where the head
gaskets rest.
4. Place heads in position and follow head torque
tightening sequence shown in Figure 9-2. Start out
tightening all capscrews, or stud nuts, to 5 ft-lbs (7
Nom), then 10 ft-lbs (14 Nom), etc., until all capscrews, or stud nuts, are tightened to the specified
torque (see Torque Specification section).
5. Retorque before engine has run a total of 25 hours.

LOW OIL PRESSURE

LEFT

RIGHT

C-1002

DRIP SHIELD
LS-1175

LEFT

FIGURE 9-1. OIL FILTER &ADAPTER

RIGHT
M-1871C

FIGURE 9-2. CYLINDER HEAD TIGHTENING SEQUENCE

9-1

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by any means, is strictly prohibited.

VALVE SYSTEM
A properlyfunctioning valve system is essential forgood
engine performance. All generator sets utilize an Lhead type valve design as shown in Figure 9-3.

Access to the valve system can be obtained by removing the cylinder heads and thevalvecoverson top ofthe
engine. A valve spring compressor must be used to
remove valves (see Figure 9-4) from the cylinder block.
Use the following procedures to inspect and service in
the valve system.

VALVE STEM

BGE

KEEPERS

NHE

VALVE CLEARANCE

A

.I

VT-1034

7/

VALVE ADJUSTING
SCREW

VALVE RETAINER

VT-1005

FIGURE 9-3.VALVE SYSTEM

VT-1D18

FIGURE 9-4. VALVE SPRING COMPRESSOR

9-2

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by any means, is strictly prohibited.

Inspection
Valve Face: Check the valve face for evidence of burning, warpage, out-of-round, and carbon deposits (see
Figure 9-5).

L

Burning and pitting are caused by the valve failing to
seat tightly. This condition is often caused by hard carbon particles on the seat. It may also be due to weak
valve springs, insufficient tappet clearance, warpage,
and misalignment.

FIGURE 9-6. VALVE STEM &VALVE GUIDE INSPECTION

FIGURE 9-5. VALVE FACE

Warpage occurs chiefly in the upper stem due to its
exposure to intense heat. Out-of-round wear follows
when the seat is pounded by a valve whose head is not
in line with the stem and guide. If a valve face is burned
or warped, or the stem worn, install a new one.
Too much clearance in the intake guide admits air and
oil into the combustion chamber, upsetting carburetion,
increasing oil consumption, and making heavy carbon
deposits. Carbon prevents heat dissipation. Clean metal
is a good heat conductor but carbon insulates and
retains heat. This increases combustion chamber
temperatures which causes warping and burning.
Unburned carbon residue gums valve stems and
causes them to stick in the guide. Deposits of hard
carbon with sharp points projecting become white hot
and cause pre-ignition and "pinging".
Valve Stem Seal: A valve stem seal is used on the intake
valve guides. This seal must be replaced each time the
valve is removed.

Springs: Check valve springs for cracks, worn ends,
distortion and tension. If spring ends are worn, check
valve spring retainer for wear. Check for spring distortion by placing spring on a flat surface next to a square.
Measure height of spring and rotate it against square
edge to measure distortion. Check spring tension at the
installed heightfor both the valve open and closed position using an accurate valve spring tester. Replace any
valve spring that is weak, cracked, worn, or distorted.

Valve Rotators (NHE exhaust only): Positivetype valve
rotators prolong valve life and decrease valve repairs.
When functioning properly, the valve is rotated a fraction of a turn each time it opens. While at open position,
the valve must rotate freely. There is no easy way to
determine if a valve rotator is good or bad. Onan
recommends that valve rotators be replaced at each
major overhaul or if a build-up of carbon is noted on
valve face and valve seat. See Figure 9-3 (NHE).

ReconditioningValves and Valve Seats
The interference angle method of valve seating is used
on all B and N series generator set engines. With this
method,different seat and face angles are usedand line
contact between the valve face and seat occurs.
The valve faceangle is 44degrees.Thevalve seat angle
is 45 degrees. This 1-degree interferenceangle results
in a sharp seating surface between the valve and top of
the valve seat (see Figure 9-7).

Stems and Guides: Always check valve stems and
guides for wear as shown in Figure 9-6. Use a hole
gauge to measurethe valve guide. When clearancewith
stem exceeds original clearance by 0.002 inch (0.05
mm), replace either valve or guide or both, as may be
necessary. Always regrind seat to make concentric with
the newly installed guide.
RIGHT

VT-lOZl

FIGURE 9-7. VALVE INTERFERENCEANGLE

9-3

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The valves should not be hand lapped because the
sharp contact will be destroyed. This is especially
important where chrome cobalt faced valves and seats
are used. Valve faces must be finished in a machine to
44 degrees.
Everyvalve must haveaminimum of 1/32-inch (0.8 mm)
margin, Figure 9-8. If the valve has less margin than this,
it will heat up excessively. It will retain that heat during
the compression stroke and pre-ignite the mixture,
causing loss of power and economy. This valve is also
susceptible to warping and breakage.
WARPED

VALVE WITH
KNIFE EDGE

GOODMARGIN

I I

Removal: Before removingvalve guides, use an electric
drill with a wire brush to remove carbon and other foreign material from top surface of guides. Failureto perform this operation may result in damage to the guide
bores. Drive the guides out with a hammer and valve
guide driver.
Driving out old guides can damage
the tappet bores. Be careful not to
strike bores wifh driver.
Installation: Run a small polishing rod with crocus cloth
through valve guide holesto clean out carbon and other
foreign materials. Place a new gasket on the intake
valve guide and coat the outer edge of each new guide
with oil. Place guide, notch up, in cylinder block and
press in until shoulder of guide rests againstthe cylinder
block. A suggested method of installation is shown in
Figure 9-9.

i

a

ROD

0.30lNCH MINIMUM

,

(.a MM)

FIGURE 9-8. VALVE MARGIN

Not all valves can be reconditioned. A badly warped
valve must be replaced becausethe excessivegrinding
required to make it seat correctly removes the margin.
To make a valve gas-tight, every trace of pitting must be
removed from the valve face and seat. Deeply pitted or
cut valves must be replaced because the grinding
removes the margin.
Valve seats should be ground with a 45-degree stone
and the width of the seat band should be 1/32-inch to
3/64-inch (0.79 to 1.2 mm) wide. Grind only enough to
ensure proper seating.

5/16-18HEX, NUT
(2 REQUIRED)

\

Place each valve in its proper location. Check each
valve for a tight seat. Make several marks at regular
intervals across the valve face using machinists bluing.
Observe if the marks rub off uniformly when the valve is
rotated part of a turn against the seat. The valve seat
should contact the valve face evenly at all points. The
line of contact should be at the center of the valve face.

Valve Guide Replacement
Worn valve stem guides can be replaced from insidethe
valve chamber (a seal is provided behind the intake
valve guides only). The smaller diameter of the tapered
valve guides must face toward the valve head. Tappets
are also replaceable from the valve chamber after first
removing the valve assemblies.

9-4

FIGURE 9-9. VALVE GUIDE INSTALLATION

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by any means, is strictly prohibited.

B

Valve Seat
Inspect valve seat inserts. I f seats are loose, cracked, or
severely pitted, new inserts must be installed. Remove
valve seat inserts using a valve seat removal tool.

Replacement: After the old seat has been removed,
clean out any carbon or metal burrs from the seat insert
recess. Use a valve seat insert driver and a hammer to
install the insert.

Removal: Remove carbon and combustion deposits
from valve seat. Select the proper size puller (determined by the inside diameter of the valve seat). The
puller jaws must expand into the cylinder block at the
point where the bottom of the valve seat insert rests on
the cylinder block (Figure 9-10). Using the new seat
insert as a guide, adjust the puller depth. Position the
puller on the valve seat and tighten hex nut. Clamp
cylinder block to a solid bench..Attach slide hammer to
puller. Between blows with the slide hammer,tighten the
hex nut.

Insertthe pilot of the tool into thevalve guide hole in the
cylinder block. Quickly drive the valve seat insert in so
that the insert goes evenly to the bottom of the recess in
the cylinder block. Make certain that the valve seat
insert rests solidly on the bottom of the recess all the
way around its circumference (Figure 9-11).
The valve seat must be staked to ensure a tight fit and
eliminate the danger of its loosening in the bore.
Insertvalve seat staker in the cylinder block valve guide
hole. Rotate the staking tool until it drops to the original
stake marks. Rotate staking tool another 60 degrees
(1/6turn). Using a lead hammer, strike the staking tool a
sharp blow to wedge the new valve seat securely in
place. Before installing valves, it will be necessary to
refinish valve seat inserts.

INSERT DRIVER
(USE PROPER TOOL)

VALVE

-

CHECK THIS SURFACE
FOR BURRS BEFORE

YT-1025

PULLERJAWS

FIGURE 9-11. INSERTING NEW VALVE SEAT

CT-1104

FIGURE 9-10. VALVE SEAT REMOVAL

9-5

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by any means, is strictly prohibited.

5. To correct the valve clearance, turn the adjusting
screw as needed to obtain the right clearance. The
screw is self-locking.
6. To adjust valves on the right cylinder, turn engine
one complete revolution and again line up mark on
the flywheel and the TC mark on the gear cover.
Then follow adjustment procedure given for left
cylinder.
7. Replace all parts removed. Tighten all screws
securely. Torque manifold bolts.

Tappet Adjustment
The engine is equipped with adjustable valve tappets.
Adjust the valve clearance only when engine is at
ambient temperature. Proceed as follows:
1. Remove all parts necessary to gain access to valve
tappets.
2. Remove spark plugs to make turning the engine
easier.
3. Place a socket wrench on the flywheel capscrew
and rotate the crankshaft in a clockwise direction
until the left intake valve (viewed from flywheel end)
opens and closes. Continue turning the crankshaft
until the TC mark on the flywheel is lined up with the
TC mark on the gear cover. This should place the
left piston (#1) at the top of its compression stroke.
Verify the left intake and exhaust valves are closed
and there is no pressure on the valve lifters.
4. Clearances are shown in the Specificationssection.
For each valve, the gauge should just pass between
the valve stem and valve tappet (see Figure 9-12).

*

GEAR COVER
Remove the flywheel key and gear cover mounting
screws. Gently tap the gear cover with a plastic-faced
hammer to loosen it (see Figure 9-1 3).
When installingthegear cover, make sure that the pin in
the gear cover engages the nylon lined (smooth) hole in
the governor cup. Turn the governor cup so the nylon
lined hole is at the three o’clock position. Use a small
amount of grease to assist in holding governor cup in
position. The rounded side of the governor yoke must
ride against the governor cup. Turn the governor arm
and shaft clockwise as far as possible and hold in this
position until the gear cover is installedflush against the
crankcase. Be careful not to damage the gear cover oil
seal.
Refer to Oil Seals section if replacing the gear cover oil
seal.

Vr-1026

FIGURE 9-12. VALVE CLEARANCE ADJUSTMENT
GOVERNOR

OVERNOR ARM
GOVERNOR SHAFT
GOVERNOR CUP
SO THAT ROLL PIN
FITS INTO THE
METAL LINED
HOLE OR PLASTIC
BUSHING IN THE CUP

.

IF FEELER WILL
ENTER HOLE 1/2 IN. (13 mm)
BALL HAS FALLEN OUT
VT-1027

FIGURE 9-13. GEAR COVER ASSEMBLY

9-6

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by any means, is strictly prohibited.

GOVERNOR CUP

TIMING GEARS AND CAMSHAFT

With the gear cover removed, the governor cup can be
taken off after removingthe snap ring from the camshaft
center pin, see Figure 9-14. Catch the flyballs while
sliding the cup off.

If replacement of either the crankshaft gear or the camshaft gear becomes necessary, it is recommendedthat
both gears be replaced.

To remove the crankshaft gear, first remove the snap
ring and retainer washer; then attach the gear pulling
ring using two No. 10-32 screws (Figure 9-15). Tighten
the screws alternately until both are tight. Attach a gear
puller to the puller ring and remove the gear.

WHEN GOVERNOR
IS PROPERLY
ASSEMBLED THE
DIMENSION SHOWN

The camshaft and gear are removed as an assembly.
Before removing the camshaft and gear assembly,
remove the cylinder head and valve assemblies. Then
remove the operating plunger for the breaker points and
tappets.

ON DRAWING WILL
BE AS INDICATED

Each timing gear is stamped with “ 0near the edge. The
gear teeth must mesh so that these marks exactly coincide when the gears are installed in the engine. When
installingthe camshaft gear and shaft assembly, besure
that the thrust washer is properly in place behind the
camshaft gear. Then install the crankshaft retaining
washer and lock ring.

GOVERNOR CUP

GOVERNOR FLYBALL
CRANKSHAFT

I

VT-1028

GEAR PULLER

FIGURE 9-14. GOVERNOR CUP

Replace with a new part any flyball which is grooved or
has a flat spot; the ball spacer if its arms are worn or
otherwise damaged; the gear/spacer assembly if loose
on gear hub, and the governor cup if the race surface is
grooved or rough. The governor cup must be a freespinning fit on the camshaft center pin, but without any
excessive play.
The governor cup and flyballs are easily installed when
the camshaft assembly is removed from the engine. If
necessary, the engine may be tilted up to install the cup
and flyballs. Put the flyballs between the spacer arms
and install the cup on the center pin. Lock the cup in
place with the snap ring.

4

Y

The camshaft center pin extends out 3/4-inch (19 mm)
from the end of the camshaft. This distance provides an
in and out travel distance of 7/32-inch (5.6 mm) for the
governor cup, as illustrated. Hold the cup against the
flyballs when measuring. If the distance is less, the
engine may race, especially at no load. Remove the
center pin and press in a new pin into place or it will be
damaged. The camshaft center pin cannot be pulled
outward or removed without damage. If the center pin
extends too far, the cup will not hold the flyballs
properly.

THESE MARKS MUST
WHEN INSTALLING
TIMING GEARS

.

vr-1019

FIGURE 9-15. TIMING GEAR REMOVAL AND INSTALLATION

9-7

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LUBRICATION SYSTEM

Oil Bypass Valve
The bypass valve (located to the right and behind gear
cover, Figure 9-17) controls oil pressure by allowing
excess oil to flow directly back to the crankcase. Normally the valve begins to open about 13-14 psi (89.696.5 kPa).

All generator set engines use an oil pump to provide a
constant flow of oil to the engine parts. The oil supply
collects in the oil base where it is picked up by the oil
pump pick-up cup. A bypass valve is used to control oil
pressure. Drain the oil before removingthe oil baseand
always use a new gasket when replacing the oil base.

HEX. CAP SCREW

Oil Pump
Theoil pump(Figure9-16)is mountedon thefrontofthe
crankcase behind the gear cover and is driven by the
crankshaft gear. The inlet pipe and screen assembly is
attached directly to the pump body. A discharge passage in the cover of the pump registers with a drilled
passage in the crankcase. Parallel passages distribute
oil to the front main bearing, rear main bearing and
pressure control bypass valve.

UMP PICK-UP CUP

LS-1110

FIGURE 9-17. OIL BY-PASS VALVE

The valve is non-adjustable and normally needs no
maintenance. To determine if abnormal (high or low) oil
pressure is caused by improper valve operation inspect
as follows:

CRANKCASETURNED
ON LEFT SIDE
LS-1109

1. Remove 3/8-24 capscrew located behind gear
cover and under governor arm.
2. Remove spring and plunger with a magnetic tool.
3. Determine proper valve operation by checking the
spring and plunger according to the following
measurements.

FIGURE 9-16. OIL PUMP ASSEMBLY

Circumferentialgrooves in the main bearings supply oil
to the connecting rod bearings through drilled passages from each main journal. A drilled passage connects the front main bearing oil supply to the front carnshaft bearing. The oil overflow from the bypass valve
furnishes lubrication to the camshaft drive gears.

Plunger Diameter

.. .... ... .. 0.3105 to 0.3125 in.

(7.89 to 7.94 mm)

Normaloil pressureshould be 13-14 psi (89.6-96.5kPa)
or higher when the engine is at normal operating
temperature. If pressure drops below this value at governed speed, inspectthe oil system for faulty components.

Spring
. .1.00 in. (25.4 mm)
Free Length
.
2.6f0.2 Ibs (11.6f0.9N)
Load..
when compressed to 0.500 in. (12.7 mm)

Check the oil pump thoroughly for worn parts. Oil the
pump to prime it before reinstalling. Except for gaskets
and pick-up cup, the component parts of the pump are
not available individually. Installa new pump assembly if
any parts are worn.

4. Check the valve seat and clean away any accumulation of metal particles which could cause erratic
valve action. Verify that the valve seat is concentric
with the larger diameter valve bore.
5. Clean plunger and spring in parts cleaning solvent
and install.

......... ... ..
... ...........

9-8

I

Y

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by any means, is strictly prohibited.

PISTON ASSEMBLY
The piston assembly consists of the piston, piston rings,
piston pin, connecting rod assembly, and bearing. After
removal from the engine, all parts must be carefully
inspected for damage and wear before replacing.

B

Removal and Disassembly
Remove carbon from top of cylinder bore and check for
a ridge. Remove ridge (see Figure 9-18) with a ridge
reamer before attempting piston removal.

4

Improper use of a ridge reamer can
damage the cylinder bore.

-1059

FIGURE 9-19. REMOVING PISTON RINGS

Remove dirt and deposits from the piston surfaces with
an approved cleaning solvent. Clean the piston ring
grooves with a groove cleaner or the end of a piston ring
filed to a sharp point (Figure 9-20). Care must be taken
not to remove metal from the groove sides.

&

FIGURE 9-18. REMOVING WEAR RIDGE

To remove the piston and connecting rod assemblies,
turn the crankshaft until a piston is at the bottom of the
stroke. Remove the nuts from the connecting rod bolts.

Y

Lift the rod bearing cap from the rod and push the rod
and piston assembly out the top of the cylinder with the
handle end of a hammer. Be careful not to scratch the
crankpin or the cylinder wall when removing these
parts.
Mark each piston and rod assembly so they can be returned to their
respective cylinders after overhaul. Keep connecting rod bearing
caps with their respective rods.

The pistons are fitted with two compression rings and
one oil control ring. Removethese rings from the piston
using a piston ring spreader as shown in Figure 9-19.
Mark each piston to make sure the rod will be
assembled on the piston from which it was removed.
Remove the piston pin retainer from each side and push
the pin out.

h

1-1

CT-1wO

FIGURE 9-20. CLEANING RING GROOVES

Using a caustic cleaning solvent or
wire brush for cleaning pistons will
cause piston damage. Use only parts cleaning solvent.

When cleaning the connecting rods in solvent, include
the rod bore. Blow out all passages with low pressure
compressed air.

9 -9

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by any means, is strictly prohibited.

Inspection
The following covers inspection proceduresfor pistons
and connecting rods.
Piston Inspection: Inspect the pistons for fractures at
the ring lands, skirts and pin bosses. Check for wear at
the ring lands using a new ring and feeler gauge as
shown in Figure9-21. Replacethe piston when the side
clearance of the top compression ring reaches 0.008
inch (0.20 mm).

Connecting Rod Inspection: Replace connecting rod
bolts and nuts with damaged threads. Replaceconnecting rods with deep nicks, signs of fractures, scored
bores or bores out of round more than 0.002 inch (0.05
mm).
Use a new piston pin to check connecting rod for wear.
A push fit clearance is required and varies from engine
to engine. If a new piston pin falls through a dry rod pin
bore as a result of its own weight, replace the rod or
bushing as required.

1

c

Pisfon Pin Inspection: Replace piston pins that are
cracked, scored, or out of round more than 0.002 inch
(0.05 mm).
Bearing Inspection:lnspect bearings for burrs, breaks,
pitting and wear. Replace bearing inserts that are
scored, have the overlay wiped out, show fatigue failure,
or are badly scratched. If bearingsappear to be serviceable, check them for proper clearance.

Piston Clearance
Proper piston tolerances must be maintained for satisfactory operation. Use a micrometer to measure the
piston diameter at the point shown in Figure9-23. When
the cylinder bore is measured (see Cylinder Blocksection), subtractthe piston diameter from the cylinder bore
diameter to obtain the piston to cylinder wall clearance.
Refer to the Dimensions and Clearancessection for the
recommended piston clearance.

'A

CT-1061

. .

FIGURE 9-21. CHECKING RING LAND

MEASURE"X' DIAMETER HERE

+

Improper width rings or excessive ring side clearance
can result in ring breakage. New rings in worn ring
grooves do not have good cylinder wall contact (Figure
9-22).

CYLINDER

.

WALL

FIGURE 9-23. PISTON CLEARANCE MEASUREMENT

Fitting Piston Rings
Before installingnew rings on the piston, check the ring
gap by placing each ring squarely in its cylinder, at a
positioncorresponding to the bottom of its travel (Figure
9-24). The gap between the ends of the ring is given in
Dimensions and Clearances section for the recommended piston clearance.

CT-1062

FIGURE 9-22. NEW RING IN WORN RING GROOVE

Replace pistons showing signs of scuffing, scoring,
worn ring lands, fractures or damage from pre-ignition.

9-

L

<

The practiceof filing ring ends to increasethe end gap is
not recommended. If the ring end gap does not meet
specifications, check for the correctness of ring and
bore sizes. A cylinder bore that is 0.001 inch (0.03 mm)
undersize will reduce the end gap 0.003 (0.08 mm).
Redistribution or publication of this document
by any means, is strictly prohibited.

Rings that are 0.005,0.010,0.020,0.030
and 0.040 inch
(0.13, 0.25, 0.51, 0.76 and 1.02 mm) oversize are to be
used on corresponding oversize pistons. Rings of the
tapered type are usually marked TOP on one side, or
identified in some other manner. Installthese rings with
the identification mark toward the closed end of the
piston.
c

&

Installing Piston in Cylinder:

1. Turn the crankshaft to position on the number one
rod bearing journal at the bottom of its stroke.
2. Lubricate the number one piston assembly and
insideof the cylinder. Compress the rings with a ring
compressor as shown in Figure 9-26.
3. Position the piston and rod assembly in the cylinder
block. Notched side of connecting rod must face
camshaft.
Rod bolts are off-set toward outside of block.

4. Tap the piston down into the bore with the handle

end of a hammer until the connecting rod is seated
on the .journal. Check bearing clearance before
proceeding with step 5 (see Rod Bearing Clearance
section).
5. Install the bearing on the rod. Install one fastener
and tighten to 5 ft-lbs (7 Nom). Repeat this for the
other fastener. Tighten both fasteners down to 14
ft-lbs (19 Nom).
6. Install the remaining piston and rod in the same
manner. Crank the engine over by hand to see that
all bearings are free.

CT-1064

FIGURE 9-24. CHECKING RING GAP

Piston Assembly Installation
1. Lubricate all parts with engine oil.
2. Position piston on its respective rod and install the
pin.
3. Install the rings on the pistons starting with the oil
control ring (Figure 9-25). Use a piston ring
spreader to prevent twisting or excessive expansion of the ring. Compression rings have a dot or the
word “top” on one side of the ring to indicate which
side faces the top of the piston. Unmarked piston
rings can be installedeither way. The oil control ring
has an expander, install the expander first and then
close until the expander ends butt. The joint should
be 180 degrees from the gap of that ring.

CT-1048

h
e

CT-1047

CT-1066

FIGURE 9-26. INSTALLING PISTON AND CONNECTING ROD

FIGURE 9-25. PISTON RINGS

9-11

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by any means, is strictly prohibited.

Rod Bearing Clearance

Lubrication
Lubricate the front and rear main bearings with engine
oil. Use oil or gear lubricant to hold the front thrust
washer in place against the engine block. The flat side of
the thrust washer goes against the block.

Mark all parts so they can be installed in their original positions, and wipe all parts dean of any oil or
grease.
Place a piece of the correct size Plasti-gage across
the full width of the bearing cap about 1/4 inch (6
mm) off center.
Install the bearing cap and tighten to the specified
torque. Do not rotate the crankshaft after the cap is
in place.
Remove the bearing cap and leave the flattened
Plasti-gage on the part to which it adheres. Compare the widest point of the flattened Plasti-gage
with the graduations on the envelope (see Figure
9-27) to determine the bearing clearance.

Position the crankshaft so the crank throw is aligned
with the notch at the rear of the crankcase and install the
crankshaft. Make sure the front thrust washer did not
slip out of place during installation.
Place the oil seal loader on the oil seal guide and driver
and insert into the rear bearing plate. Remove the seal
guide and driver leaving the loader in the bearing plate.
The loader prevents the seal from being cut on the
crankshaft keyway during installation of the rear bearing plate.

1

b

Use oil or gear lubricant to hold the shim(s) and rear
thrust washer in position on the rear bearing plate (see
Figure 9-32). The shim goes against the bearing plate
and the flat surface of the thrust washer goes against the
shim.
Place the bearing plate gasket in position on the block,
making sure the oil hole on the back of the block is
exposed. Install the rear bearing plate and fasten with
two nuts (or capscrews) tightened to the specified
torque. Makesure the rear thrust washer and shim(s) did
not slip out of place during installation. The crankshaft
should turn freely by hand.

Checking Endpiay

-1OB7

FIGURE 9-27. MEASURING BEARING CLEARANCE

CRANKSHAFT
To remove the crankshaft, loosenthe rear bearing plate
screws and remove the bearing plate, gasket, thrust
washer, and shims. Turn the crankshaft so the crank
throw is aligned with the notch in the rear opening of the
crankcase. Carefully slide the crankshaft out of the
crankcase.

After tightening two rear bearing plate nuts (or capscrews) to the specified torque, check the crankshaft
endplay at the point shown in Figure 9-28 using a feeler
gauge. Lightly tap the front of the crankshaft with a
plastic-faced hammer to take up the freeplay. Refer to
the Dimensions and Clearancessection for the recommended crankshaft endplay. If necessary, remove the
rear bearing end plate and add or remove shims as
required. Install the end plate and tighten all nuts (or
capscrews)to the specified torque. Make sure the shim
and thrust washer are in place, and recheck crankshaft
endplay. Verify that the crankshaft turns freely without
binding.

inspection
Inspect the rod and main bearing journals. If they are
worn or scored and cannot be smoothed out by polishing, either the journals should be reground to use oneof
the standard undersize bearings or the crankshaft
should be replaced. Remove only as much metal as is
requiredto restorethejournal surface while maintaining
the recommended bearing clearance.
Whenever making major repairs on the engine, always
inspect the drilled passages of the crankshaft. Clean
them to remove any foreign material and to provide
proper lubrication of the connecting rods.

9-12

MEAIUAE ENDPLAY HERE
(REFER TO DIMINIIONB
AND CLEARANGEE)

1

CT-IO((

FIGURE 9-28. CHECKING ENDPLAV
Redistribution or publication of this document
by any means, is strictly prohibited.

CYLINDER BLOCK
The cylinder block is the main support for all other basic
engine parts. Crankshaft and camshaftare supported by
the block, assuring alignment of the crankshaft and
cylinder bores.

?

4

Cleaning
After removing pistons, crankshaft, cylinder heads, etc.,
inspect block for cracks and extreme wear. If block is
still serviceable, prepare it for cleaning as follows:
1. Scrape all old gasket material from block. Remove
oil bypass to allow cleaning solution to contact
inside of oil passages.
2. Remove grease and scale from cylinder block by
agitating in a bath of commercial cleaning solution
or hot soapy washing solution.
3. Rinse block in clean hot water to remove cleaning
solution.

Inspection
When rebuilding the engine, thoroughly inspect block
for any condition that would make it unfitfor further use.
This inspection must be made after all parts have been
removed and block has been thoroughly cleaned and
dried.

A. Measure and record as “A” the cylinder bore
diameter (parallelto crankshaft) near the top of
cylinder bore where greatest amount of wear
occurs.
6. Also measure and record as “B’cylinder bore
diameter (parallelto crankshaft)atthe bottom of
piston travel.
C. Measure and record as “C” cylinder bore
diameter (perpendicular to crankshaft) near the
top of cylinder bore where greatest amount of
wear occurs.
D. Also measure and record as “D” cylinder bore
diameter (perpendicular to crankshaft) at the
bottom of piston travel.
E. Reading “A” subtracted from reading “ B I and
reading “C“ subtracted from reading “D” indicates cylinder taper.
F. Reading“A” comparedto reading“C”and reading “ 6 compared to reading “D’ indicates
whether or not cylinder is out-of-round. If outof-round exceeds 0.003 inch (0.08 mm), the
cylinders must be reboredand honedto the next
oversize. A reboring machine is used when
going to oversize pistons. The following repair
data covers honing to oversize by use of a hone.

1. Make a thorough check for cracks. Minute cracks
may be detected by coating the suspected area with
a mixture of 25 percent kerosene and 75 percent
light motor oil. Wipe the part dry and immediately
apply a coating of zinc oxide (white lead) dissolved
in wood alcohol. If cracks are present, the white
coating will become discolored at the defective
area. Always replace a cracked cylinder block.
2. Inspect all machined surfaces and threaded holes.
Carefully remove any nicks or burrs from machined
surfaces. Clean out tapped holes and clean up any
damaged threads.
3. Check top of block for flatness with a straight edge
and a feeler gauge.

Cylinder Bore Inspection: Inspect cylinder bores for
scuffing, scratches, wear, and scoring. If cylinder bores
are scuffed, scratched, scored, or worn, they must be
rebored and honed for the next oversize piston.

TOP END OF CYLINDER

When the appearance of cylinder bores is good and
thereareno scuff marks, checkcylinder boreforwear or
out of roundness as follows:
U

I

1. Check cylinder bore for taper, out-of-round, and
wear with a cylinder bore gauge, telescope gauge,
or inside micrometer.These measurementsshould
betaken at four places,top and bottom of piston ring
travel and parallel and perpendicular to axis of
crankshaft.
2. Record measurements taken at top and bottom of
piston travel as follows (see Figure 9-29).

9-13

RING
WEAR
AREA

BOlTOM OF RING TRAVEL

c-1090

FIGURE 9-29. METHODS OF MEASURING THE
DIAMETER OF A CYLINDER BORE
Redistribution or publication of this document
by any means, is strictly prohibited.

5. Check diameter of the cylinder regularly during honing. A dial bore gauge is the easiest method, but a
telescoping gauge can be used. Check size at six
places in bore; measure twice at top, middle, and
bottom at 90-degree angles.
6. Crosshatch formed by the stones should form an
included angle of 23degrees. This can be achieved
by moving the rotating hone (250to 450 rpm) up and
down in cylinder bore about 40 times per minute.
7. Clean cylinder bores thoroughly with soap, water
and clean rags. A clean white rag should not
become soiled on wall after cleaning is complete.
Do not useasolventor gasoline, since they wash oil
from the walls but leave metal particles.
8. Dry crankcase and coat with oil.

Reboring the Cylinder
Rebore and hone engine whenever cylinder bore is
worn, damaged, out-of-round, or if cylinder taper
exceeds specifications. A worn cylinder bore should be
resized to the smallest standard oversize diameter at
which it will clean up. The final finish and bore diameters
should then be obtained by honing.
If boring bar is operated incorrectly,
it will produce a rough cylinder surface that may not clean up even when honed. Boring
should be done only by qualified service personnel
who are careful in their work.

1-1

After boring to the correct oversize, cylinder bore
dimension, piston and ring clearance should be appropriate. There is no need to adjust or “fit” pistonsand rings.
When reboring cylinders, take the following precautions:
Make sure cutting tool is properly ground before
using it.
Be sure top of engine block is smooth and deposit
free.
Clean base of boringbar before bar is set up. Deposits under boring bar will cause it to tilt, and the
cylinder will be distorted after boring.
Make an initial rough cut, followed by a finish cut.
Then hone cylinder bore to the specified oversize.

9

#

Deglazing Cylinder Bores
Deglaze the cylinder bores if there are no scuff marks
and no wear or out of round beyond specifications
before installingnew rings. Deglazinggivesafinefinish
but does not enlarge cylinder diameter, so the original
pistons with new rings may still be used.
The reason for deglazinga cylinder is to providecavities
to hold oil during piston break-in.
1. Wipe cylinder bores with a clean cloth which has
been dipped in clean, light engine oil.
2. Use a brush type deglazing tool with coated bristle
tips to produce a crosshatch pattern in the cylinder
bore.
3. The deglazing tool should be driven by a slow
speed drill. Move deglazing tool up and down in
cylinder (10 to 12 complete strokes) rapidly enough
to obtain a crosshatch pattern as shown in Figure
9-30.

Honing Cylinders (Using Precision Hones)
Refer to hone manufacturer’srecommendedgrit size to
produce specified surface finish of 20 to 40 RMS. Too
rough of a finish will wear out the rings and too smooth
of a finish can retard piston ring seating.
1. Position blocksolidly for either vertical or horizontal
honing. Use either a drill press or heavy-duty drill
which operates at approximately 250 to 450 rpm.
2. Follow hone manufacturer’sinstructions for the use
of oil or lubricant on stones. Do not use lubricants
with a dry hone.
3. Insert hone in bore and adjust stone to fit snugly to
the narrowest section. When adjusted correctly, the
hone should not shake or chatter in cylinder bore,
but will drag freely up and down when hone is not
running.
4. Connect drill to honeand start drill. Feel out borefor
high spots, which cause an increased drag on
stones. Move hone up and down in bore with short
overlapping strokes about 40 times per minute.
Usually bottom of cylinder must be worked out first
because it is smaller. As cylinder takes a uniform
diameter, move hone up and down all the way
through cylinder bore.

... .

PRODUCECROSS HATCH
SCRATCHES FOR FAST
RING SEATING

AVOID THIS FINISH
c-1091

FIGURE 9-30. CROSSHATCHING

9-14

Redistribution or publication of this document
by any means, is strictly prohibited.

Never use gasoline or commercial cleaners io clean cylinder
bores after deglazing or honing. These solvents
will not remove abrasives from the walls. Abrasives not removed from engine will rapidly wear
rings, cylinder walls, and bearing surfaces of all
lubricated pa&.

4, Clean cylinder bore thoroughly with soap, water,
and clean rags. Continue cleaning until a clean
white rag shows no discoloring when wiped through
cylinder bore.

BEARINGS
With camshaft and crankshaft removed, usea micrometer to measure diameter of bearing journals. Use a dial
bore gauge or a telescopic gauge and micrometer to
measure inside diameter of bearings. Refer to Dimension and Clearance section to determine if clearances
are within specifications.

Crankshaft Bearings
New crankshaft main bearings are precisiontype which
do not require line reaming or line boring after installation. They are available in standard size, 0.002, 0,010,
0.020 or 0.030 inch undersize.

For putting in either the front or rear main bearing,
always align the oil hole@)in the bearing with the oil
hole(s) in the bearing bore. The oil passage must be at
least 112 open.
Before installing main bearings, expand bearing bore by
placing the casting in an oven heatedto 2OO0F(94"C). If
practical, cool the precision bearing to shrink it.
Rear Bearing:Use the combination main and cam bearing driver and a press to install the rear main bearing.
Push the bearing into the bearing plate from the inner
side (see Figure9-32) to the depth allowed by the flange
on the driver.
REAR BEARING END PLATE

Any bearing that is scored, chipped, pitted or worn
beyond the specified limits must be replaced.

&

ALIGN BEARING OIL HOLES
WITH OIL HOLES IN BEARING

Camshaft Bearings
Replacementcamshaft bearings are precisiontype and
do not require line reaming or line boring after installation. Coat the bearing with lubricating oil. Position the
front bearing so the oil hole in the bearing isaligned with
the oil hole see (Figure 9-31) in the block. Position the
rear bearing so the elongated slot is aligned with the
breaker point plunger hole in the top of the block.

THRUST WASHER

1 I,.

M-I415

BEARING
PRECISION TYPE

- DO NOT LINE BORE OR REAM

FIGURE 9-32. REAR BEARING

Front Bearing: Locktite Bearing Mount is used when
installing the front bearing. Use the towelette furnished
with the bearing kit to clean the outside of the bearing
and the bearing bore in the block. Allow three to four
minutes for drying.
IN BEARING BORE I

M-1474

Breathing vapor from towelette and
k&@%l
prolonged contact wifh skin can be
harmful. Use only in well ventilated area and avoid

FIGURE 9-31. CAMSHAFT BEARING

Use the combination main and cam bearing driver and a
press to install the front and rear cam bearings. Push in
the bearings to the depth allowed by the flange on the
driver.

9-15

prolonged confact wiih skin.

Redistribution or publication of this document
by any means, is strictly prohibited.

Apply the LocktiteBearing Mount to the mating surfaces
of the bearing and bearing bore. Use the combination
main and cam bearing driver and a press to instal1
the
front bearing. Push the bearing in to the depth allowed
by the flange on driver. Wipe off any excess Locktite and
allow one hour for hardening at room temperature.
Engines shipped from the factory have separate thrust washers and
main bearings for both front and rear of engine. Front bearing
replacement part is one piece bearing (with attached thrust washer)
as shown in Figure 9-33. Do not add an additional thrust washer to
this front bearing.

NOTE: DO NOT ADD ADDITIONAL
THRUST WASHER WHEN
REPLACING FRONT BEARING

OIL SEALS
R~~~~~ the rear bearing plate to
the rear oil
seal. Removethe gear cover to replacethe front oil seal.
Use an oil seal removed to pry out the front or rear oil
seal,

Use an oil seal guide and driver to press or drive the rear
seal into the rear bearing plate until it bottoms against
the shoulder of the plate (see Figure 9-34). Press or
drive the front seal into the gear cover until it is 0.97 f
0.02 inch (24.6 k 0.5 mm) from the mountingface of the
cover.
Lubricate the lips of the replacement seal with a light
coating of grease before installing the rear bearing plate
or gear cover. This provides initial lubrication until
engine oil reaches the seal. Refer to the Crankshaft
section for the rear bearing plate installation procedures. Referto the Gear Cover section for the gear cover
installation procedures.

FRONT
MAIN BEARING
BORE

ALIGN BEARING
NOTCHES WITH
LOCK PINS AND
MATCH OIL HOLES

FRONT
MAIN BEARING
PRECISION TYPE
DO NOT LINE BORE OR REAM OR
BORE

M-1476

FIGURE 9-33. FRONT BEARING

USE GREASE IN
SPACE BETWEEN
SEALS TO IMPROVE

GEAR COVER

MOUNTING FACE
OF GEAR COVER

THIS SURFACE SHOULD BE
CLEANED OF ALL OLD
SEALING COMPOUND
BEFORE INSTALLING
SEAL

OIL SEAL

0.97 f 0.02 INCH
(24.6 f 0.5 mm)

i

THIS SURFACE SHOULD BE
CLEANED OF ALL OLD SEALING
COMPOUND BEFORE
INSTALLING SEAL

GEAR COVER OIL SEAL

DRIVE OR PRESS OIL
SEAL TO SHOULDER
OF THE PLATE BORE

REAR BEARING PLATE
OIL SEAL
m-1477

FIGURE 9-34. OIL SEALS

9-16

Redistribution or publication of this document
by any means, is strictly prohibited.

Section IO. Service Checklist
After servicing, inspect and test the complete installation to confirm that the generator set will operate properly and will pull full rated load. Check each of the
following areas before putting the set into service.

4

MOUNTING

.(

Examine all mounting bolts and supporting members to
verify that the generator set is properly mounted. All
fasteners should be tightened securely to prevent them
from working loose when subjected to vibration.

LUBRICATION
If the engine oil was drained,fill thecrankcase with oil of
the recommended classification and viscositv. Refer to
the appropriate operator’s manual for the specific
recommendations and procedures.

FUEL SYSTEM
With the generator set operating, inspectthe fuel supply
lines, filters, and fittings for leaks. Check any flexible
sections for cuts, cracks and abrasions and make sure
they are not rubbing against anything that could cause
breakage.
Leaking fuel will create a fire hazard
which can result in severe personal
injury or death if ignited by a spark, flame, or other
ignition source. If leaks are detected, correct
immediately.

OUTPUT CHECK
Applyafull loadto makesurethesetwill produceitsfull
rated output. Use a load test panel to apply a progressively greater load until full load is reached.

WIRING
Verify that all wiring connections are correct and
secure. Check each of the following:
0
0

Load Wires
Control Wires
Ground Strap
Battery Cables

INITIAL START ADJUSTMENTS
Adjust the carburetor idle and main adjustment screws
as specified in the Fuel System section.

1-1

EXHAUST SYSTEM
With the generator set operating, inspect the entire
exhaustsystem including the exhaust manifold, muffler,
and exhaust pipe. Visually and audibly check for leaks
at all connections, welds, gaskets, and joints and also
make sure exhaust pipes are not heating surrounding
areas excessively. If leaks are detected, correct
immediately.

1-1

Inhalation of exhaust gases can
result in severe personal injury or
death. Inspect exhaust system audibly and visually for
leaks daily. Repair leaks immediately.

Before attempting any carburetor/
governoradjustments,disconnect all
devices which are voltage or frequency sensitive.
Some solid-state devices, such as TV’s or VCR’s, are
powered whenever connected to an AC outlet even if
the device is not in actual operation. If disconnecfing
the devices is not possible, open the circuit breaker(s)
at the distributionpanelor at the genset, if so equipped.

Stop and start the generator set several times at the set
control and remote control (if equipped) to verify the
control functions properly.

Failure to heed this advisory may result in consequential damage to voltage/frequencysensitive equipment
such as VCR’s, TV’s, computers, etc. Repairheplacement of damaged devices is not covered under Onan
warranty policy.

Stop the generator set and inspect for leaking gaskets,
loose fasteners, damaged components, or interference
problems. Repair as required. Inspectthe generator set
compartmentand verify there are no breaksor openings
in the vapor-proof wall that separatesthe compartment
from the vehicle interior. Seal openings as required.
Make sure all soundproofing material is in place.

d

Start the set and immediately adjust the governor speed
adjustment nut to obtain a safe no-load operating
speed. With no load applied, listen for any unusual
sounds or vibrations. When the choke is completely
open, adjust the carburetor and governor as specified in
the Fuel System section.

‘

CONTROL

MECHANICAL

10-1

Redistribution or publication of this document
by any means, is strictly prohibited.

IAWARNING I
EXHAUST GAS IS DEADLY!
Exhaust gases contain carbon monoxide, an odorless and colorless gas. Carbon
monoxideis poisonous and can causeunconsciousnessand death. Symptoms of
carbon monoxide poisoning can include:
0

Dizziness
Nausea
Headache
Weakness and Sleepiness

0
0
0

Throbbing in Temples
Muscular Twitching
Vomiting
Inability to Think Coherently

IF YOU OR ANYONE ELSE EXPERIENCE ANY OF THESE SYMPTOMS, GET OUT
INTO THE FRESH AIR IMMEDIATELY. If symptoms persist, seek medical attention. Shut down the unit and do not operate until it has been inspected and
repaired.
Never sleep in vehicle with the generator set running unless the vehicle interior is
equipped with an operatingcarbon monoxidedetector. Proiecfion against carbon
monoxide inhalation also includes proper exhaust systeminstallation and visual
and audible inspection of the complete exhaust system at the start of each
generator set operation.
1-RV

10-2

Redistribution or publication of this document
by any means, is strictly prohibited.

Appendix A. Troubleshooting Charts
R

These pages form an appendix to the service manual. This informationwas prepared by the Onan Service
Training Department in the form of simplifiedguides to troubleshooting a variety of the circuit boards usedon
the BGElNHEgeneratorsets. while this informationis accurate, make sureto follow the completeprocedures
outlined in the appropriate service manual sections for reasons of safety and product integrity.

Q

A-2: “Troubleshooting Electronic Ignition Module”
A-3, A-4: “EmeraldTMControl Functions”
0

0

A-5, A-6: “Emerald Control Board Checkout (300-2784)“
A-7, A-8: “Emerald Control Board Checkout (300-3056/3687)”
A-9, A-1 0: “Emerald Control Board Checkout (300-3763-01, -02)”

A-I

Redistribution or publication of this document
by any means, is strictly prohibited.

Troubleshooting Electronic
Ignition Module
Models: PerformerTM,Emerald PlusTM,
MarquisTM,
Ensignm
Test 1

Test

Ignition
- __

1.

Check wiring: red lead to positive (+);
black lead to negative

2.

Connect a DC powered test light from
the negative (-) coil terminal to
ground.

3.

Turn the ignition switch on and crank
the engine over. Does the test light
flash, bright then dim?

e).

Yes

Ignition
Module

No

-

- The module is ok; do net
replace the module.
Go to Test 2.

-

Note: If the primary winding of the
ignition coil is open, the light will not
come on.

Test 2

Test
Light

4.

Connect the test light from the
positive (+) coil terminal to ground.

5.

Turn the ignition switch to the on
position. Does the light come on?

Trigger
Ring

Yes

- the
Crank the engine over. Does
light stay on while

Yes

- Replace the module and the

cranking?

No

I

-

Module

trigger ring as a set if the coil
tests good.
It is not a module problem.
Check the wiring and
connections to the coil and
the ignition switch, then retest
the module.

I AWARNING I

_ _ _ ~

Use extreme caution when working on operating equipment Operating equipment presents hazards of electrocution,
bums, fire and explosion, asphyxiation, and entanglement with rotating parts. Review Important Safety instructions in
Operator’s Manual.
Performer, Emerald Plus, Marquis, Ensign are trademarks of Onan Corporation
@ 1991 Onan Corporation

A-2

Redistribution or publication of this document
by any means, is strictly prohibited.

900-0261

Emerald'" Control Functions
(AI Control Board 38013056/3687)
4

*

Engine Cranking Start Mode

Sequence of Events:
Battery + @os) at PI-6,
Battery (neg) at P1-8.

-

Operator pushes start button at AI.

B+ from PI-2 to start solenoid
(S terminal).
Solenoid contacts close send B+ to
starter.

Sequence of Events:

Ignition Start Mode

Operator pushes start button on AI.
E3
SPARK
PLUG

Safeties are bypassed.
B+ from P3-3 to ignition coil.

IGNVON COIL

-

Breaker points open/close path to
ground.
S

High voltage jumps spark plug gap.
B+ supplied to fuel pump from PI-2.
b

1AWARNING I
Use exlreme cautlon when woMng on
opntlng generator sets. Operating
-generator sets presents hazards ofelectrucufion, bums, tlre and exploslon, asphyxlatlon, and entanglementwith rvtatlng parts. Review Important Safe'etyIn-

ET1
BATTERY

FUEL PUMP
Es2Mn2c

I

structions In Operator's Manual.

A-3

Redistribution or publication of this document
by any means, is strictly prohibited.

FiHKFlaXStart Mode

Sequence of Events:
Operator pushes start button on
AI.
B+ from P1-5to voltage regulator
P4-7.

.-

,

I

B+ from voltage regulator P4-9 to
positive brush (Fl).

B- from voltage regulator P4-10 to
negative brushes (F2).

Kl

A1 BOARD

m

Sequence of Events:
I.

I

Engine starts, oil pressure causes
LOPKO to close sending ground
signal to P3-4.

lgn%ion Run Mode

E3
SPARK

AC from generator B1-B2 winding
enter board at P1-1 and P1-7.

PLUG

I w

IGNITION COIL

-

These two inputs cause the contra1
tu switch from staH mode to run
mode.

Starter automatically disengages.
Field flash automatically removed.
Start switch released.
Safeties enabled.
Bl-B2 powers choke heater (Hl).
Pump power now from P3-6
through R7.

Sequence of Events:

Battery Charging Run Mode

I

AC voltage from B1-82 windings
enter board at P I-1, P I-7.

Board rectifies AC input to DC outPut

B+ charge current from P1-6flows
to battery.
R6 on ground side limits charging
current to 1amp maximum.
A-4

Redistribution or publication of this document
by any means, is strictly prohibited.

EMERALD

Conlinuous

-

Circuit Good

COHTlNUlTY

CONTROL BOARD
CHECK-OUT
(300-2784)

3

-

Many Emerald control problems are caused
by a bad connection between the PC board
and the wiring harness. Check continuity at
the eight terminals.

1

STATICMODE

V

Battery voltage

(E)
12 VDC Good

40

10 O o 0

STATIC MODE

-

3

STATIC MODE

Battery voltage

B+ at P1-6. BAlTERY POSITIVE INTO BOARD
Ground at P1-7 & 8.
Required: 12-14 VDC

[AWARNING 1

5

Working on operating generator sets presents
hazards of electrocution, burns, fire and explosion, asphyxiation, and entaglement with rotating
pa&
Review Important Safety Instructions in
Operator's Manual.
Es1050r

STATIC MODE

A-5

Redistribution or publication of this document
by any means, is strictly prohibited.

START MODE
Push SI switch to start.
B+ at P1-2, P1-3 and P1-5.
Required: 10-12 VDC

B+ AT P1-2 TO START SOLENOID
b+ AT P I 3 TO IGNITION COIL
B+ AT P1-5 TO POS BRUSH
(FIELD FLASH)

RUN MODE
1. AC voltage at P1-1 to P1-7
(18-26 VAC) BAT CHARGER
2. B+ at P1-3 to IGNITION COIL
3. Ground at P1-4 FROM LOPKO
Required: 18-26 VAC
12-14 VDC

STOP MODE

Push SI switch to stop.
0 volts at PI-3
I

le

(BZJ

I

STOP/STATIC MODE

A-6

Redistribution or publication of this document
by any means, is strictly prohibited.

EMERALD
CONTROL BOARD
CHECK-OUT
(300-305613687)

0

REMOVE CIRCUIT BOARD
To perform the following tests the circuit board
must be removedfrom the control cover.

..

CONTINUITY TEST
Place the circuit board on a non-conductive surface
with the component side of the board up.
Check for a good clrcuit between the board and the
wiring by checking contlnuity between the J and P
connectors with the battery disconnected.

For the following tests, the battery must
be connected.

STATIC MODE
in the Center position)
Meter
Reading
12 VDC
12 VDC

A-7

Redistribution or publication of this document
by any means, is strictly prohibited.

CRANK & START MODE
(Wlth the switch pressed to the Start position)

Meter
Test Lead

Meter

P1-2 P2-1
P1-5 P2-1
P3-3 P2-1

9-10 VDC
10-11 VDC
9-10 VDC

+

-

6

RUN & GENERATE MODE
(With the generator set running and the switch
In the Center position)

Meter
Test Lead

Meter
Reading

Pl-6
P1-6
P2-5
P2-6
P3-3
P3-4
P3-6

P2-1
P1-4
P2-1
P2-1
P2-1
P2-1
P2-1

12-13 VDC
18-20 VDC
12-13 VDC
12-13 VDC
10-12 VDC
0 VDC
10-12 VDC

P1-1 P1-7

18-22 VAC

+ -

STOP MODE
(With the switch pressed to the Stop position)
Meter
Test Lead

Meter
Reading

P3-4 P1-8
P3-4 P2-1

0 VDC
0 VDC

+

-

Redistribution or publication of this document
by any means, is strictly prohibited.

EMERALDIMARQUIS
CONTROL BOARD
CHECK=OUT
(300-3763-01,02)
MODELS:
BGE Spec. F & G
BGEL Spec. E & G
NHE, NHEL Spec. D, E & G
BGM, NHM Spec. A
BGD Spec. A & B
NHD Spec. A, B & C
P I plug turned for better viewing.

REMOVE CIRCUIT BOARD

To perform the following tests the circuit board
must be removed from the control cover.
Place the circuit board on a non-conductive surface
with the component side of the board up.

P1
For the following tests, the battery must
be connected.

STATIC MODE

IAWARNING I
*

Use extreme caution when worklng on operating
generator sets. Operating generator sets presents
hazards of electrocution, bums, fire and-explosion,
asphyxiatlon, and entanglement with rotating parts.
Review Important Safety Instructions In Operator's
Manual.
EmeraldMarquis is a trademark of Onan Corporation
0 1991 Onan Corporation
A-9

(With the switch in the Center position)
Meter
Test Lead

Meter
Reading

PI-7 PI-11
PI-7 J2-1

12 VDC
12 VDC

+

-

Redistribution or publication of this document
by any means, is strictly prohibited.

CRANK & START MODE
(With the switch pressed to the Start position)
Meter.
Test Lead

PI

+

PI-1
PI4
PI-9
P1-12
* PI-7

-

I

10-12 VDC
10-12 VDC
10-12 VDC
10-12 VDC
10-12 VDC

52-1
52-1
J2-1
J2-I
PI-IO

RUN tk GENERATE MODE

L

...

Meter
Reading

(With the generator set running and the
switch in the Center position)
Meter
Reading

Meter .
Test Lead

P1
PI-7
PI-7

PI-3 NIA BGDNHD
PI-5

18-20 VDC
10-13 VDC

PI-2

PI4

18-22 VAC

-

STOP MODE
(With the switch pressed to the Stop position)
L

PI

Meter
Test Lead

Meter
Reading

PI -6

0 VDC
0 VDC

+

*

-

52-1
P I-12 J2-1
P1-7 PI-IO

*

12 VDC

Gensets with K5 relay
Redistribution900-0265
or publication of10191
this document
by any means, is strictly prohibited.

Appendix 6. Spec J and K Diagrams
c

This appendix contains DC control schematic and wiring diagrams for t h e Spec J and Spec K BGE and NHE
generator sets.
GENERATOR SET

h

DIAGRAM NUMBER

Spec J BGE/NHE 60 HZ....... 611-1206
Spec J BGUNHE 50 Hz ....... 611-1207

.... 611-1208
Spec K BGUNHE 60 Hz ...... 611-1220
Spec K BGUNHE 50 HZ ...... 611-1221
Spec K BGE 60 Hd100 V ..... 611-1222
Spec J BGE, 60 Hz, 100 V

PAGE

.................................................
5 2
................................................. 5 3
................................................. E 3 4
................................................. E-5
................................................. B-6
.................................................
57

Redistribution or publication of this document
by any means, is strictly prohibited.

Redistribution or publication of this document
by any means, is strictly prohibited.

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SCHEMATIC

SPEC J BGUNHE 60 HZ WIRING DlAGRAMlSCHEMATlC

8-2

I MODIFIED
Redistribution or publication of this document
by any means, is strictly prohibited.

I

* T 2 L3

T4 L3

I10/120V

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SCHEMATIC

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WIRING DIAGRAM
SPEC J BGE/NHE 50 HZ WIRING DIAGRAWSCHEMATIC

I MODIFIED
B-3

Redistribution or publication of this document
by any means, is strictly prohibited.

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SPEC J BGE 60 HUlOO V WIRING DIAGRAM/SCHEMATIC

8-4

I NO. 611-1208
REV. A
MOblFlED

Redistribution or publication of this document
by any means, is strictly prohibited.

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SCHEMATIC

WIRING DIAGRAM

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SPEC K BGUNHE 60 HZ WIRING DlAGRAMlSCHEMATlC

I MODIFIED
Redistribution or publication of this document
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SPEC K BGUNHE 50 HZ WIRING DlAGRAMlSCHEMATlC

8-6

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Redistribution or publication of this document
by any means, is strictly prohibited.

A2

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SCHEMATIC

WIRING DIAGRAM
SPEC K BGE 60 HUlOO V WIRING DIAGRAWSCHEMATIC

NO. 6111222
MODIFIED

6-7

Redistribution or publication of this document
by any means, is strictly prohibited.

Redistribution or publication of this document
by any means, is strictly prohibited.

Instruction Sheet
6−2000
C351e
Installation of Control Board Replacement
Kit 300-3950
PURPOSE OF KIT

BGM/NHM MOUNTING CONSIDERATIONS

These instructions describe the removal and replacement of the Control Circuit board used on the
following generators.

If installing the kit on a BGM/NHM (Marquis) generator set, note the following change:

BGE . . . . . . . . . . . . . .
BGEL . . . . . . . . . . . . .
NHE, NHEL . . . . . . . .
BGM, NHM . . . . . . . .
BGD . . . . . . . . . . . . . .
NHD . . . . . . . . . . . . . .

Spec F and G
Spec E and G
Spec D, E and G
Spec A only
Spec A and B
Spec A, B and C

SAFETY PRECAUTIONS
Read these instructions completely and become familiar with safety warnings, cautions, and procedures before starting the installation.
Always disconnect a battery charger
from its AC source before disconnecting the battery
cables. Otherwise, disconnecting the cables can result in voltage spikes high enough to damage the DC
control circuits of the set.
Accidental starting of the generator set
while working on it can cause severe personal injury
or death. Prevent accidental starting by disconnecting the starting battery cables (negative [−] first).

KIT PARTS
Prior to installation, verify receipt of the proper parts
from the table below.
Part Description

QTY.

Splice, Window; 22−16

6

Screw, Pan Head; 6−32 x .38

4

Harness, Wire, PCB

1

PCB, Control Assembly

1

The lead marked J1-12-E2 MUST be connected
to K5, pin 85 instead of the marked connection.
Disregard the wire routing labels in this
instance only.
Consult Figure 3 (J1 diagram) for more information.
This note applies only to technicians installing the
Control Board kit on the BGM/NHM (Marquis) gensets.
Incorrect installation, service, or parts
replacement can result in severe personal injury,
death, and/or equipment damage. Service personnel
must be qualified to perform electrical and mechanical installions and service.

INSTALLATION
Tools Required
• Wire stripping and splicing tool
• Torx screwdriver kit
• Needle-nose pliers
• Conventional screwdriver kit

Procedure
1. Disconnect the generator set starting battery
cables (negative [−] cable first) to prevent the
genset from starting.
2. Turn off and disconnect battery charger (if
equipped).
3. Pull the genset fuse from the control panel and
set it aside. Disconnect the remote cable, if
present.
4. Remove the two screws from the top of the control panel. Pull the panel down and away from
the control box.
Page 1 of 4

5. Pull connectors J1 and J3 off the edge of the
Control Circuit board. Remove the wires from
the control panel wire retainer (Figure 1).
6. Remove the four screws securing the circuit
board to the control panel and pull the board off
the panel. Discard the old board and screws.
7. Mount the new circuit board from the kit onto
the control panel using the no. 6 screws in the
kit.

Wires on the new connector are labeled for connecting wires in the control box. Connect the wires
one at a time. Do not cut away or obscure the labels on the wires, wherever possible.
1. Attach the new connector J1 to the wires in the
control box as follows:
A. Using the stripping/splicing tool, strip 1/4
inch off one of the wires from the control
box.
B. Insert the end of the wire into one of the
wire splice connectors.

CONTROL PANEL
ATTACHMENT
SCREWS

C. Crimp the connector firmly onto the wire
using the splicing tool.

J1
CONNECTOR

GENSET
MAIN FUSE

BATTERY
POSITIVE (+)
CONNECTION
J3
CONNECTOR

FIGURE 1: CONTROL PANEL ASSEMBLY
(EARLIER VERSION w/J1 and J3 CONNECTORS)

Build New Connector
1. Cut connectors J1 and J3 from the wires extending into the generator set control. Clip
wires as close to the connector as possible.
Make sure the routing labels on the wires
remain intact.
If the routing labels are missing, refer to Figure
3 and Table 1, and refer to the wiring diagram/
schematic for the genset.
2. Using the stripping/splicing tool, crimp the 6
splices to the wires extending from the new J1
connector supplied in the kit. Insert the wires
one-by-one into the connectors, then crimp the
connectors firmly onto the wires using the splicing tool.
C351e
Page 2 of 4

Wiring

D. Repeat this step for each of the wires attached to new J1 connector.
NOTE: Wire J1−3 is not used. Use a tie wrap to
coil and secure this wire, or remove the wire.

When installing on a Marquis
(Models BGM and NHM) be sure to connect
J1-12 to K5, pin 85. Connecting this lead to
E2 as marked, will short out the control
board, and the genset will not run.
2. Remove the remaining non-terminated wires
one at a time, replacing them with new wires
from J1.
3. Connect the five push-on terminals from connector J1 to the designated connectors inside
the genset using the needle-nose pliers (Table
1).
4. The terminal marked K1−s may have two
wires. Clip the wire tie holding them together to
connect the new K1−S. Secure the terminal
with a new wire tie.
5. Plug new J1 connector onto the control board.
6. Tuck all wires neatly back into the control box. if
possible, pull the wires back into the control
box from the rear of the box.
7. Four of the wires connecting to new J1 pass
through the front of the control box. Clip these
wires to the retainer located on the lower, inside
edge of the control board to secure them in
place (Figure 2).

Reassemble

CONTROL
BOARD

1. Position the control panel on front of the control
box. Reattach the control panel using the two
screws removed in Step 4.

P2 BOARD
CONNECTOR:
ATTACH NEW
J1 HERE

2. Connect the positive (+) battery cable to the
terminal at the front of the control box.
3. Connect the negative (−) battery cable to the
terminal on the generator set.
4. Reconnect the battery charger (if equipped).
5. Install the main fuse in the control panel.
6. Start and test the genset according to the appropriate operator’s manual.
Electrical shock can cause severe personal injury or death. Do not touch electrical wiring
or components during testing. Disconnect electrical
power by removing starting battery negative (−)
cable before handling electrical wiring or components.

WIRE RETAINER

FIGURE 2: BACK OF CONTROL PANEL
(REPLACEMENT PANEL)

J1
ROUTE LEAD TO:

ROUTE LEAD TO:
7 − K1−1 (B+ POWER TO BOARD)

J4−7 (TO VR1) − 1

8 − NOT USED

B1 (FROM GENERATOR − 2

9 − K1−S

R6 (NOT USED) − 3

10 − BGE/NHE−NOT USED BGEL/NHEL−CR6
ALL OTHERS−CR8
11 − GROUND (L0)

B2 (FROM GENERATOR − 4
S2 (LOPKO) − 5
E1 (IGNITION COIL) − 6

12 − E2 OR R7 (K5 ON BGM/NHM)

FIGURE 3. J1 PIN CONNECTIONS
TABLE 1. LABELS ON HARNESS LEADS
New Wire Labels
Near Connector J1

Original Wire Labels
Furthest From
Connector

J1−1

J1−5

J4−7 (to VR1)

J1−2

J1−1

B1

J1−3

J1−4

Not used on 3951 board; R6 on 3950 board

J1−4

J1−7

B2

Component Connection

C351e
Page 3 of 4

J1−5

J3−4

New Wire Labels
Near Connector J1

Original Wire Labels
Furthest From
Connector

J1−6

J3−3

E1 (Ignition coil +)

J1−7

J1−6

K1−1

J1−8

−−−

Not used

J1−9

J1−2

L1−S (May be piggybacked to CR9−E2 or K6−85)

J1−10

J3−2

BGE/NHE − Not used; BGEL/NHEL − CR6;
BGM/NHM and BGD/NHD − CR8

J1−11

J1−8

GND (L0)

J1−12

J3−6

BGM/NHM − K5−85; Models with R7 resistor − R7;
All others − Pump E2

C351e
Page 4 of 4

S2 (LOPKO)
Component Connection

Curnrnins Power Generation
1400 73rd Avenue N.E.
Minneapolis, M N 55432

763-574-5000
Fax: 763-574-8087
Cummins and Onan are registeredtrademarks of Cummins Inc.

Redistribution or publication of this document
by any means, is strictly prohibited.



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