Cummins/Onan HGJAD — Specs, Engine, Parts & Maintenance

Service parts for the HGJAD

Grouped by system, with how many of each the parts manual calls for.

Air intake

1 required

0140-3116Air filter$9.95eBay

Fuel system

1 required

0147-0860Fuel filter$4.68NAPA

Oil system

1 required

0122-0836Oil filter$10.59eBay

Ignition

1 required

0167-1638Spark plug$11.95eBay

Prices captured from merchant listings; some links are affiliate links. Confirm against your serial number before ordering.

Specifications

Fuel	gasoline
Frequency	60.0 Hz
Controller	A1, EC-AGS+
Oil capacity	1.8 L
Voltage options	120/240 V, 120 V
Phase	1
Rated current	58.3 A
Power factor	1.0
Battery cranking	450 CCA
Battery voltage	12 V
Dry weight	132 kg
Sound level	66.0 dBA @ 3 m

Filters & service parts

model family

Item	Spec	Capacity	Part #	Interval
Air filter			0140-3116		Amazon eBay $9.95
Fuel filter			0147-0860		Amazon eBay $16.99 NAPA $4.68
Oil filter			0122-0836		Amazon eBay $10.59
Battery	12 V; Min. Battery CCA 450 @ 0°F (–18°C); genset provides up to 10 amps regulated charging		—	10000 hr
Belt			—	30000 hr
Coolant		3.7 L	—	1000 hr
Oil	15W-40 (OnaMax) multigrade recommended year round		—	500 hr
Spark plug			0167-1638		Amazon eBay $11.95

Compiled from this model's family documentation — may include parts for closely-related variants. Confirm the exact part for your serial number.

Service intervals

Item	Action	Hours	Months	Notes
Genset	Other	1 hr	1 mo	Exercise at least 1 hour each month at approximately 1/2 rated power if use is infrequent
Engine oil level	Check	8 hr		First service — Section 4.2
Exhaust system	Inspect	8 hr		Inspect for exhaust leaks at every startup and after every eight hours of running
General inspections	Inspect	8 hr		Every day or every 8 hours
Genset	Inspect	8 hr		Every day or every 8 hours; general inspections
Genset general inspection	Inspect	8 hr		Before first start of the day and after every 8 hours of operation
Engine oil	Change	50 hr		In dusty environments change engine oil every 50 hours
Spark arrester	Clean	50 hr		Every 50 hours
Spark arrestor	Clean	50 hr		Table 3-1 Periodic Maintenance Schedule
Air filter element	Replace	450 hr		Perform more often when operating in dusty environments
Engine cooling fins	Clean	450 hr		Perform more often when operating in dusty environments
Engine oil & oil filter	Change	150 hr	12 mo	First service — Perform more often in dusty environments and hot weather; at least once a year
Engine oil and oil filter	Change	150 hr	12 mo	First service — Perform more often in dusty/hot environments; at least yearly
Fuel filter	Replace	500 hr	36 mo	Sooner if engine performance deteriorates; by trained mechanic
Cylinder heads	Clean	500 hr		Clean or replace; required for optimum performance
Spark plugs	Replace	500 hr		Sooner if performance deteriorates
Valve lash	Adjust	500 hr		Must be performed by trained mechanic (authorized Cummins dealer)
Battery	Clean		1 mo	Clean and check monthly (more often in hot weather)
Battery and battery connections	Clean		1 mo	Perform more often in hot weather

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Service specifications

Type	Item	Value	Unit	Condition
Clearance	Crankshaft End Play	0.005 - 0.012	in
Clearance	Crankshaft End Play	0.127 - 0.305	mm
Clearance	Crankshaft Oil Seal depth below surface	0.020 to 0.060	in
Clearance	Crankshaft end play	0.005 – 0.012	in (0.127 – 0.305 mm)
Clearance	Crankshaft end play	0.005-0.012	in
Clearance	Crankshaft oil seal press depth	0.020 to 0.060	in	below surface
Clearance	Cylinder head flatness max	0.004	in
Clearance	Cylinder head flatness maximum	0.004	in (0.1 mm)
Clearance	Exhaust Valve Lash (Cold)	0.10	mm (0.004 in)	cold
Clearance	Intake Valve Lash (Cold)	0.10	mm (0.004 in)	cold
Clearance	Piston-to-cylinder clearance at skirt max	0.0098	in
Clearance	Valve guide inside diameter max	0.242	in
Clearance	Valve guide inside diameter standard	0.2376 – 0.2383	in (6.035 – 6.053 mm)
Gap	Magneto Air Gap	0.012	in (0.3 mm)
Gap	Magneto Air Gap	0.3	mm
Gap	Spark Plug Gap	0.025	in (0.6-0.7 mm)
Gap	Spark Plug Gap	6-7	mm (0.025 in)
Injection timing	Ignition Timing	20 deg BTDC	degrees BTDC	non-adjustable magneto
Other	EC-AGS+ gateway dimensions	120 x 108 x 38	mm
Other	Ignition Timing	20° BTDC		non-adjustable magneto
Other	LPG low-pressure supply (vapor)	9-13	in WC
Other	Maximum exhaust back pressure	35	in WC
Other	Spark plug kit torque specification	18-25	lb-ft
Other	Temperature sensor dimensions	51 x 70 x 17	mm
Pressure	Carburetor fuel pump outlet pressure	2.5 to 4	psi	priming
Pressure	Compression	3.9	kgf/cm2 (55.47 lbf/in2)	@ 500 RPM
Pressure	Crankcase Vacuum	7 to 10	inches of water column	measured through a tap in the oil fill cap
Pressure	Crankcase vacuum	7-10	inches water column	measured through oil fill cap tap
Pressure	Cylinder Compression Test	153-188	psi
Pressure	Engine Compression	153 and 188	psi
Pressure	Fuel Pump pressure (carburetor models)	2.5 to 4	psi (17 to 27 kPa)
Pressure	Fuel Rail Pressure (EFI)	43.5 psi (300 kPa) nominal	psi
Pressure	Fuel rail pressure differential	43.5	psi	nominal
Pressure	Gasoline EFI fuel pressure (between fuel rail and high pressure fuel pump, priming)	approximately 45	psi	generator set off and priming
Pressure	Hydraulic Pump Inlet Conditions	5	in Hg Vacuum or 20 psi Pressure max
Pressure	Hydraulic Pump Inlet Conditions	Not to exceed 5 in Hg Vacuum or 20 psi	in Hg / psi
Pressure	Hydraulic pump	1.6	gpm @ 2500 psi	5.5 model pumps
Pressure	Hydraulic pump	1.8	gpm @ 2500 psi	HGJAD/HGJAE pumps
Pressure	LPG Vapor Supply Pressure	9-13	in (228-330 mm) WC
Pressure	LPG supply pressure (low-pressure)	9-13	in (228-330 mm) WC	all loads
Pressure	Low Oil Pressure Cutoff	less than 17	psi
Pressure	Low Oil Pressure Fault threshold	less than 17	psi
Pressure	Low oil pressure fault threshold	17	psi	less than 17 psi
Pressure	Low oil pressure switch opens	14.2	psi
Pressure	Low-Pressure LPG demand regulator lock-off pressure	0.20 to 0.35	inches WC
Pressure	Low-Pressure LPG supply pressure	9-13	inches WC
Pressure	Low-pressure LPG lock-off pressure	0.20 to 0.35	inches WC (5.1 to 8.9 mm)
Pressure	Max Exhaust Back Pressure (HGJAF models)	35	in (889 mm) WC
Pressure	Max exhaust back pressure	35	in (889 mm) WC
Pressure	Nominal Engine Oil Pressure	43	psi
Pressure	Nominal oil pressure	43	psi
Pressure	Oil Pressure (nominal)	43	psi
Pressure	Oil Pressure Switch (opens)	14.2	psi
Resistance	Fuel Injector resistance	12.5	Ohms
Resistance	Fuel injector electrical resistance	approximately 12.5	ohms
Resistance	Gateway harness continuity maximum resistance	10	Ohms	repair or replace harness if greater
Resistance	Governor actuator stator winding	4.5 and 5.5	ohms
Resistance	Ignition Coil LEFT (No. 1 Cyl) maximum	33,000	Ohms
Resistance	Ignition Coil LEFT (No. 1 Cyl) minimum	13,700	Ohms
Resistance	Ignition Coil RIGHT (No. 2 Cyl) maximum	27,000	Ohms

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Recommended fluids

Fluid	Grade	Standard	Ambient	Capacity	Notes
Engine oil		API Class SJ, SH or SG		2.0 quart (1.8 l)	Oil capacity
Engine oil	OnaMax 10W-30 (A063E183)	API SM, SN, or better		1.8 l	Recommended for temperatures above 0 °F
Engine oil	5W-30	API SJ, SH or SG (may combine with CH-4, CG-4 or CF-4)	-28°C to 10°C		–20° F to 50° F (–28° C to 10° C)
Engine oil	SAE 5W-30	API Class SJ, SH or SG (may be combined with CH-4, CG-4 or CF-4)	-28°C to 10°C		–20°F to 50°F
Engine oil	10W-30	API SJ, SH or SG (may combine with CH-4, CG-4 or CF-4)	-18°C to 27°C		0° F to 80° F (–18° C to 27° C)
Engine oil	10W-30 (OnaMax), 10W-40	API SM, SN, or better	-18°C to 38°C		-18 to 38 °C (0 to 100 °F)
Engine oil	10W-30 10W-40	API SJ, SH or SG (with CH-4, CG-4 or CF-4)	-18°C to 27°C	1.8 l	0 deg F to 80 deg F (-18 deg C to 27 deg C)
Engine oil	10W-30, 10W-40	API SJ/SH/SG (may combine CH-4, CG-4, CF-4)	-18°C to 27°C
Engine oil	10W-40	API SJ, SH or SG (may combine with CH-4, CG-4 or CF-4)	-18°C to 27°C		0° F to 80° F (–18° C to 27° C)
Engine oil	SAE 10W-30 / 10W-40	API Class SJ, SH or SG (may be combined with CH-4, CG-4 or CF-4)	-18°C to 27°C		0°F to 80°F
Engine oil	15W-40 (OnaMax)	API SJ, SH or SG (may combine with CH-4, CG-4 or CF-4)	-12°C to 38°C		10° F to 100° F (–12° C to 38° C)
Engine oil	SAE 15W-40 (OnaMax)	API Class SJ, SH or SG (may be combined with CH-4, CG-4 or CF-4)	-12°C to 38°C		10°F to 100°F
Engine oil	30	API SM, SN, or better	above 0°C		0 °C (32 °F) and higher
Engine oil	SAE 30	API SJ, SH or SG (may combine with CH-4, CG-4 or CF-4)	above 0°C		32° F (0° C) and higher; single-grade SAE 30 preferable when temperatures consistently above freezing
Engine oil	10W-30 / 10W-40		18°C to 27°C	1.8 liters (2.0 qt)	-18 to 27°C (0 to 80°F)
Fuel	HD-5 LPG, min 90% propane				Commercial LPG may contain up to 2.5% butane
Fuel	HD-5 grade LPG (at least 90 percent propane)				Commercial LPG may contain more than 2.5 percent butane causing poor vaporization/starting below 32° F (0° C)
Fuel	HD-5 grade LPG (min 90% propane)				LPG models; butane >2.5% prevents vaporization below 32 °F (0 °C)
Fuel	HD-5 grade LPG or equivalent, at least 90 percent propane				LPG models; commercial LPG may contain more than 2.5% butane
Fuel	HD-5 grade liquefied petroleum gas (LPG)	at least 90 percent propane			LPG models. Commercial LPG may contain more than 2.5 percent butane causing poor vaporization below 32 F (0 C).
Fuel	HD-5 grade liquefied petroleum gas (LPG), at least 90% propane				Butane content may result in poor vaporization below 32 °F (0 °C)
Fuel	HD-5 grade liquified petroleum gas (LPG), at least 90 percent propane	Commercial LPG may contain more than 2.5 percent butane			LPG models; low-pressure LPG vapor pressure per Specifications
Fuel	Unleaded gasoline	minimum octane rating (Anti-Knock Index) of 87			Gasoline models. Do not use gasoline containing methanol.
Fuel	Unleaded gasoline, min 87 octane				Not more than 10% ethanol; not more than 5% methanol
Fuel	Unleaded gasoline, min octane 87 (Anti-Knock Index)	Max 10% ethanol; max 5% methanol with solvents/corrosion inhibitors			Gasoline models
Fuel	Unleaded gasoline, min. octane rating (Anti-Knock Index) 87	Ethanol blend not more than 10% ethanol; methanol blend not more than 5% methanol with solvents and corrosion inhibitors			Gasoline models
Fuel	Unleaded gasoline, minimum octane rating (Anti-Knock Index) 87				Do not use gasoline/additives containing methanol; avoid leaded gasoline
Hydraulic oil	Transmission or Petroleum-Based Hydraulic Fluid				Operating Viscosity: 80-1000 SSU; Maximum Start-Up Viscosity: 4000 SSU
Hydraulic oil	Transmission or petroleum-based hydraulic fluid	Operating viscosity 80-1000 SSU; maximum start-up viscosity 4000 SSU			Optional hydraulic pump models HGJAD/HGJAE/HGJAF

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Fault codes

Code	Name	Meaning	Severity	Action
1	High Engine Coolant Temperature	Status indicator light blinks 1 time - shutdown due to high engine coolant temperatures	Shutdown	Allow engine to cool; inspect cooling system
12	Overvoltage Shutdown	Instantaneous: AC voltage S1-S2 greater than 150 VAC. Delayed: greater than 138 VAC but less than 150 VAC for 3 continuous minutes	Shutdown	Verify FC12; measure AC voltage; cycle loads; reduce battery charge rate; balance loads; run in ERO mode; measure winding resistances; check brush alignment.
13	Undervoltage Shutdown	Controller unable to maintain rated voltage	Shutdown	Verify FC13; measure AC voltage in/out of sense transformer; cycle loads; reduce charger rate; measure winding resistances; check brush alignment.
14	Overfrequency Shutdown	Instantaneous: frequency greater than 70 Hz. Delayed: greater than 66 Hz but less than 70 Hz for 3 continuous seconds	Shutdown	Verify FC14; measure AC current and load capability; check governor, fuel supply, air filter, exhaust, choke, magnetos; run ERO test.
15	Underfrequency Shutdown	Engine governor unable to maintain rated frequency.	Shutdown	Verify FC15; measure AC current; check governor, fuel supply, air filter, exhaust, choke, magnetos; run ERO test.
17	Fuel Pump Fault	Open fuel pump circuit at control (active prior to 2001)	Shutdown	Verify pump in prime mode; check fuse F1; replace pump
19	Governor Actuator Shutdown	Shorted or open connection between governor leads after pressing start; P1-17	Shutdown	Verify actuator function with DC voltage; measure actuator terminal resistance; check P1-28 continuity
2	Low Oil Pressure Shutdown	Low oil pressure cutoff switch did not open.	Shutdown	Verify FC2; measure oil level; inspect P1 pins per PSB-676; measure continuity; measure oil pressure with a mechanical gauge; repair/replace relief valve and oil pump.
22	Governor Actuator Overload Shutdown	Only active prior to 2001; maximum governor output (PWM) for 10 continuous seconds.	Shutdown	Verify FC22; measure AC current, load capability; check air filter, intake manifold gaskets, exhaust, fuel pump pressure; verify actuator; check magnetos.
23	Oil Pressure Switch Fault	Only active prior to 2001 - continuous open on oil pressure switch input before cranking	Shutdown	Verify harness lead connected; measure continuity to ground at switch and through harness at P1
27	Voltage Sense Shutdown	No sense voltage (0 VAC across S1-S2) for 1 continuous second after start disconnect.	Shutdown	Verify FC27; measure AC voltage; inspect P1 pins; check air filter and exhaust; run ERO test; check fuel and ignition systems.
29	High Battery Voltage Shutdown	Voltage across battery system is greater than 19 Volts.	Warning	Verify FC29; measure DC voltage at battery, generator set and P1; check grounds; replace controller if needed.
3	Service Check Shutdown	Single-digit fault indicating shutdown due to a two-digit fault	Shutdown	While LED flashing three times, press stop once (1 second) and troubleshoot the two-digit fault code.
31	Overspeed Shutdown	Engine speed greater than 3400 rpm	Shutdown	Verify FC31; measure frequency and droop; check governor, air filter, exhaust, fuel, magnetos; run ERO test.
32	Low Cranking Speed Shutdown	Quadrature frequency less than or equal to 3 Hz and engine RPM less than or equal to 100 RPM for 12 continuous seconds after pressing start.	Shutdown	Verify FC32; measure battery voltage; verify engine rotation; check starter, air filter, spark plug, exhaust; check magnetos.
33	Fault Code 33	There is a single-digit fault which indicates a shutdown due to a two-digit fault code; Fault Code 3 interpreted as a non-assigned Fault Code 33.	Shutdown	While LED flashing three times, press stop once (1 second); troubleshoot the two-digit fault code.
35	Control Card Failure Shutdown	Microprocessor EEPROM error occurred during self test.	Shutdown	Verify FC35; replace the control.
36	Stopped Without Fault Condition	RPM less than 500 and sense voltage S1-S2 at 0 VAC with no other fault	Shutdown	Verify FC36; check AGS; verify engine rotation; inspect P1 pins; check air filter, spark plug, exhaust; run ERO test.
37	Invalid Set Configuration	Wrong frequency/rpm ratio	Shutdown	Verify FC37; if alternating with FC47 reset magneto gap; run ERO test; measure winding resistances; verify magnetos and board.
38	Overcurrent (Field Overload) Shutdown	Low power factor loads.	Shutdown	Verify FC38; measure F1-F2 DC voltage and AC current; reduce charger rate; inspect P1 pins; measure winding resistances; check brush alignment.
4	Overcrank Shutdown	First-level shutdown code—Cranking exceeded 30 seconds without engine starting (4 blinks)	Shutdown	Verify FC4; measure battery voltage; check start/stop switch and P1; check air filter, spark plug, exhaust system, fuel supply, ignition and magnetos.
41	Generator Rotor Shutdown	Only active after 2003; field voltage F1-F2 at 0 VDC and sense voltage S1-S2 at 0 VAC for 1 continuous second.	Shutdown	Verify FC41; measure F1-F2 DC voltage and AC current; inspect P1 pins; run ERO test; measure winding resistances; check brush alignment.
42	Processor Shutdown	ROM error during self-test	Shutdown	Verify FC42; replace the control.
43	Processor Shutdown	RAM error during self-test	Shutdown	Verify FC43; replace the control.
45	Speed Sense Shutdown	While running, the quadrature frequency dropped to 0 Hz for 1 continuous second.	Shutdown	Verify FC45; check AGS; verify engine rotation; inspect P1 pins; check air filter, exhaust, loads; run ERO test; check magnetos.
47	Ignition Shutdown	No ignition signal at P1 (P1-15 for HGJAB/C; P1-5 for HGJAA/D/E/F) for 1 continuous second	Shutdown	Verify FC47; if alternating with FC37 reset magneto gap; test magnetos; run ERO test; measure winding resistances.
48	Generator Field Sense Shutdown	The controller is unable to sense field voltage.	Shutdown	Verify FC48; replace the control.
51	Processor Shutdown	Processor error; faulty control	Shutdown	Verify FC51; use breakout board per Instruction Sheet R1098; replace the control.
52	Fuel Injector Shutdown	Open or shorted fuel injector; P1-17; wire connections	Shutdown	Verify FC52; inspect injector connector and P1 pins; measure continuity between P1-23 INJ1 and P1-35 INJ2; replace injector.
54	MAT Sensor Fault (EFI)	The MAT sender input is greater than 300k Ohms.	Shutdown	Verify FC54; inspect sender connector and P1 pins; measure continuity between P1-25 MAT(A) and P1-20 MAT(B); replace sender.
56	MAP Sensor Fault (EFI)	The MAP sensor input is less than 50 kPa at start.	Shutdown	Verify ambient pressure; test sender; replace sender
57	Overprime Shutdown	The generator set has been priming for 3 consecutive minutes.	Shutdown	Verify FC57; check for an object holding the switch in stop position; inspect P1 pins; check start/stop switch.
58	Exhaust Gas Temperature Shutdown	Exhaust gas temperatures reach 650C (1202F) for 2 secs when the set is running	Shutdown	Verify FC58; check spark plugs and cables; test magnetos; check carburetor/LP mixer/regulator/EFI injector; check EGT sensor and wiring; check compression and leakdown.
81	Overprime Shutdown	While running, the EGT falls below 60 °C (140 °F) for 2 minutes or is not above 60 °C 2 minutes after starting.	Shutdown	Verify FC81; check connector at muffler and harness; check wiring; measure resistance between EGT sensor connector and J1-15/J1-21; use InPower; replace the EGT sensor.
82	Exhaust Gas Temperature Sensor Shorted	With the set running and/or startup - control reads 1000C (1832F) for 1 second	Shutdown	Verify FC82; measure resistance between ground and J1-21; use InPower; replace the EGT sensor if a short exists.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Procedures

Adjusting Governor (Mechanical) adjustment

⚠ Voltage/frequency-sensitive equipment may be damaged by power line frequency variations; disconnect them before adjustments.

Tools: Variable load bank up to 7 kW, Frequency meter (within 0.3%), Voltmeter (within 0.5%), AC ammeter

Warm up the genset for at least 5 minutes at 1/2 to 3/4 rated load with the choke fully open.
Adjust frequency close to the Table 8-3 value with the speed adjusting nut.
With the engine warm, remove all loads and adjust the idle stop screw to 51-53 Hz (60 Hz genset) or 41-43 Hz (50 Hz genset).
Let the throttle lever go and recheck/adjust No-Load frequency to Table 8-3; bump the governor arm to check stabilization.
Connect rated load; if droop is out of spec move the governor spring hook one or two notches and recheck.
Confirm the governor does not hunt under the loading sequence.

Adjusting Governor (Mechanical, HGJAB and HGJAE) adjustment

⚠ Disconnect all voltage/frequency-sensitive devices before making carburetor/governor adjustments.

Tools: Variable load bank up to 7 kW, Frequency meter (within 0.3%), Voltmeter (within 0.5%)

Warm up generator set for at least 5 minutes at 1/2 to 3/4 rated load.
Adjust frequency with the speed adjusting nut toward the Table 11 value.
With engine warm, remove all loads; adjust idle stop screw to 51-53 Hz (60 Hz) or 41-43 Hz (50 Hz).
Let throttle lever go.
Recheck and re-adjust no-load frequency per Table 11.
Bump governor arm to see frequency stabilizes.
Connect a rated load.
If droop is greater than specified, move governor spring hook one or two notches toward governor shaft; recheck.
If droop is less or set hunts, move spring hook one or two notches away from governor shaft.

Adjusting Mechanical Governor adjustment

⚠ Voltage/frequency-sensitive equipment may be damaged; disconnect before adjusting

Tools: load bank, frequency meter, voltmeter

Warm up genset five minutes at 1/2 to 3/4 rated load.
Adjust frequency to Table 8-4 value with speed adjusting nut.
With engine warm and no loads, set idle stop screw to 51-53 Hz (60 Hz).
Recheck no-load frequency and bump governor arm for stability.
Connect rated load; move governor spring hook to correct droop.
Check for hunting under the specified load sequence.

Adjusting Valve Lash adjustment

Tools: Socket wrench, Feeler gauge, Torque wrench

Adjust when the engine is at room temperature.
Remove the spark plugs so the engine is easier to turn over.
Use a socket wrench on the generator pulley nut to turn the engine clockwise; remove the snap-in cover.
Remove the valve covers with rags in place to catch oil.
Turn engine until No. 2 intake valve is at max lift; adjust No. 1 intake valve lash.
Turn engine until No. 2 exhaust valve is at max lift; adjust No. 1 exhaust valve lash.
Turn engine until No. 1 intake valve is at max lift; adjust No. 2 intake valve lash.
Turn engine until No. 1 exhaust valve is at max lift; adjust No. 2 exhaust valve lash.
Secure valve covers using new gaskets and torque cover screws to 5.5 lb-ft (8 N-m).
Replace the spark plugs and pulley nut cover.

Adjusting Voltage adjustment

⚠ If fault shutdown or STOP pressed during voltage set mode, adjustment is not stored

Tools: AC voltmeter, Frequency meter

Disconnect all alternator loads.
Connect accurate AC voltmeter and frequency meter.
Start genset and let voltage/frequency stabilize 5-10 seconds.
Rapidly press control switch to START 6 times within 1 minute.
Press START briefly to raise voltage ~0.6 V per press.
Press START for ~2 seconds to lower voltage ~0.6 V per press.
Normal operation resumes 20 seconds after last adjustment.

Resetting Governor Arm adjustment

Tools: Battery terminal puller, Torque wrench

Loosen the governor shaft nut by turning it clockwise and remove the arm.
Use a battery terminal puller to break the taper fit of the shaft in the arm hub.
Reattach arm and hub making sure the pins and holes engage; thread the shaft nut on counterclockwise.
Check free rotation of the arm and let the governor spring take up all play; linkage must push throttle against the wide open throttle stop.
Torque the shaft nut to 8 lb-ft (11 N-m) counterclockwise.
Push the governor arm down and check for binding or interference.

Setting Ignition Coil Air Gaps adjustment

Tools: Feeler gauge, Torque wrench

Bar the engine until the lands on the flywheel directly face the coils.
Place a 0.012 inch (0.03 mm) thick feeler gauge between the coil and the land.
Hold the coil tight against the feeler gauge and land and torque the two mounting bolts to 5 lb-ft (7 N-m).

Setting Magneto Air Gaps adjustment

Tools: feeler gauge, torque wrench

Bar the engine until the flywheel lands directly face the coils.
Place a 0.012 inch (0.3 mm) feeler gauge between coil and land.
Hold coil tight against gauge and land.
Torque the two mounting bolts to 5 lb-ft (7 N-m).

Valve Lash Adjustment adjustment

⚠ Adjust valve lash only when engine is at room temperature

Tools: Feeler gauge, Socket wrench, Torque wrench

Adjust valve lash with engine at room temperature.
Remove spark plugs and valve covers.
Turn engine until No. 2 intake valve is at maximum lift.
Adjust No. 1 intake valve lash to 0.004 in (0.10 mm).
Turn engine until No. 2 exhaust valve at maximum lift; adjust No. 1 exhaust.
Turn engine until No. 1 intake valve at maximum lift; adjust No. 2 intake.
Turn engine until No. 1 exhaust at maximum lift; adjust No. 2 exhaust.
Torque lock nuts to 6.5 lb-ft (8.5 Nm) and install valve covers.

Voltage Adjustment (HGJAD, HGJAE, HGJAF) adjustment

⚠ Hazardous voltage: touching uninsulated live parts can cause severe injury or death

Tools: AC voltmeter, frequency meter

Disconnect all generator loads and connect accurate AC volt and frequency meters.
Start genset; let voltage and frequency stabilize 5 to 10 seconds.
Rapidly press control switch to START 6 times within 1 minute of start.
Adjust up: press START and release quickly (voltage rises about 0.6 volt).
Adjust down: press START and release after about 2 seconds (voltage drops about 0.6 volt).

Fuel Pump Flow Test (EFI Gasoline Models) diagnostic

⚠ Gasoline is flammable; do not smoke; keep ignition sources away

Tools: Fuel pressure gauge, Gallon container

Disconnect fuel return line between genset and tank.
Collect fuel in a gallon container.
Prime the genset for exactly one minute.
Verify flow is approximately 1 quart (0.9 liter) per minute.
Verify fuel pressure is approximately 45 psi.
Reconnect the fuel return line.

Fuel Pump Flow Test (EFI) diagnostic

⚠ Gasoline is flammable and explosive

Tools: gallon container, fuel pressure gauge

Disconnect the fuel return line between genset and supply tank.
Be prepared to collect fuel in a gallon container.
Prime the genset for exactly one minute.
Verify flow is approximately 1 quart (0.9 liter) per minute and pressure about 45 psi.
Reconnect the fuel return line.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Voltage reconnection

Voltage	Phase	Connection	Leads	Notes
		These generator sets are not reconnectable for voltages other than stated on the nameplate		AC output through rain-tight 1/2 inch conduit connector; 12 AWG leads, 125 °C rated wire
100-120	1-Phase	2-Wire	T1-T2 and T3-T4 in phase, neutral L0 and ground	The two generator windings marked T1-T2 are in phase; neutral conductors must carry the sum of the currents
100-120V	1	"2-wire"	CB1-LOAD (L1), CB2-LOAD (L2), NEUTRAL (L0)	Not reconnectable; generator windings T1-T2 are in phase so neutral conductors must be sized to carry the sum of the currents
100/200	1-Phase	standard 3-Wire	T1-T2, T3-T4 with neutral L0	Not reconnectable
100/200V, 115/230V, 120/240V	1	Standard 3-wire	CB1-LOAD (L1), CB2-LOAD (L2), NEUTRAL (L0)	These are not reconnectable generators; 12 AWG AC output leads through rain-tight 1/2 inch trade size conduit connector
110/120	3-Phase	standard 3-phase	T1-T2, T3-T4, T5-T6 with neutral L0	Not reconnectable for voltages other than stated on the nameplate
110/120V, 115/230V, 120/240V	3-phase	3-phase	CB1-LOAD (L1), CB2-LOAD (L2), CB3-LOAD (L3), NEUTRAL (L0)	These are not reconnectable generators
115/230	1-Phase	standard 3-Wire	T1-T2, T3-T4 with neutral L0	Not reconnectable
115/230	3-Phase	standard 3-phase	T1-T2, T3-T4, T5-T6 with neutral L0	12 AWG leads exit through rain-tight 1/2 inch trade size conduit connector
120	1	2-wire 120 VAC; alternator leads T2 and T4, green AC output lead and two white (L0, L0) leads secured to base with alternator neutral ground screw	T2, T4, L0, L0, green	2-wire 120 VAC configuration only
120/240	1-Phase	standard 3-Wire	T1-T2, T3-T4 with neutral L0	Not reconnectable
120/240	3-Phase	standard 3-phase	T1-T2, T3-T4, T5-T6 with neutral L0	Not reconnectable

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Common questions

Is the Cummins/Onan HGJAD diesel or gas?

The Cummins/Onan HGJAD runs on gasoline.

How much oil does the Cummins/Onan HGJAD take?

The Cummins/Onan HGJAD has an engine oil capacity of 1.8 liters (1.9 US quarts), per the manufacturer specification sheet.

How loud is the Cummins/Onan HGJAD?

The Cummins/Onan HGJAD is rated at 66.0 dBA at 3 m, per the manufacturer specification sheet.

How much does the Cummins/Onan HGJAD weigh?

The Cummins/Onan HGJAD has a dry weight of 132 kg (291 lb).

What voltages is the Cummins/Onan HGJAD available in?

The Cummins/Onan HGJAD is offered in 120/240 V, 120 V, 1-phase.

How many cold cranking amps does the Cummins/Onan HGJAD require?

The Cummins/Onan HGJAD uses 12 V each, 450 CCA, per the manufacturer specification sheet.

What oil filter does the Cummins/Onan HGJAD use?

The Cummins/Onan HGJAD uses oil filter part number 0122-0836.

What fuel filter fits the Cummins/Onan HGJAD?

The Cummins/Onan HGJAD uses fuel filter part number 0147-0860.

What air filter fits the Cummins/Onan HGJAD?

The Cummins/Onan HGJAD uses air filter part number 0140-3116.

Troubleshooting

Fault codes

Code	Meaning
2	Low Oil Pressure Fault
3	Service Check Fault
4	Overcrank
12	Overvoltage
13	Undervoltage
14	Overfrequency

Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing. Full Cummins/Onan HGJAD troubleshooting guide (37 entries) →

Repair guides

Step-by-step procedures compiled from the Cummins/Onan service manual for this model.

Parts

Part #	Description	Qty	System
A060Z343	Oil filter, air filter, EFI fuel filter, spark plug, (2) Onamax oil		Air filter	Amazon eBay

Service, wear & replacement parts referenced for this model and its engine — confirm the exact part for your serial number. See the full parts catalog to search and cross-reference.

Fuel consumption

Rating	Load	L/h	gal/h
		1.6	0.43
	50%	2.7	0.7
	100%	4.3	1.13
Continuous		1.6	0.43
Continuous	50%	2.7	0.7
Continuous	100%	4.3	1.13

Available documents

Operator's manual (Cummins/Onan)Operator's manual — 6758 Owners Manual (Cummins/Onan)Operator's manual — 983-0102 Onan HGJA Series (spec A-E) Mobile Genset Operators manual (07-2011) (Cummins/Onan)Reference (Cummins/Onan)Reference — 983-0601 Onan HGJAD (spec A-E) HGJAE (spec A-E) HGJAF (spec A-D) Mobile Genset Installation Manual (11-2014) (Cummins/Onan)Owner's manual — 983-0601B Onan HGJAD HGJAE HGJAF Mobile Genset Installation Manual (07-2005) (Cummins/Onan)Owner's manual — Onan-EC-AGS Manual (Cummins/Onan)Parts manual — 0058719 (Cummins/Onan)Parts manual — Cummins Onan Commercial Mobile Accessories 1 (Cummins/Onan)Parts manual — HGJAD, HGJAE, HGJAF Parts Manual (Cummins/Onan)Service manual — 983-0501 Onan HGJAA to HGJAF (spec A-D) RV Genset Service manual (02-2010) (Cummins/Onan)Service manual — 983-0501D Onan HGJAA HGJAB HGJAC HGJAD HGJAE HGJAF Mobile Genset Service manual (01-2006) (Cummins/Onan)Service manual — A035D011 SERVICE i23-HGJAA HGJAB HGJAD HGJAE(Spec J-M)7-22 (Cummins/Onan)Service manual — HGJAA, HGJAB, HGJAC, HGJAD, HGJAE, HGJAF Service Manual (Cummins/Onan)

This page was generated from the 14 manufacturer documents above by automated extraction; every figure shown is copied from one of them. How the data is compiled.

Cummins/Onan HGJAD Generator Set

Service parts for the HGJAD

Air intake

Fuel system

Oil system

Ignition

Specifications

Filters & service parts

Service intervals

Service specifications

Recommended fluids

Fault codes

Procedures

Voltage reconnection

Common questions

Troubleshooting

Fault codes

Repair guides

Parts

Fuel consumption

Available documents