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Cummins/Onan QG 4000 Generator Set

The Cummins/Onan QG 4000 is a 4 kW (4 kVA) gasoline prime generator set. It is available at 120 V, Single-phase, 50 Hz and rated 33.3 A. The set measures 762×500.38×365.76 mm (30.0×19.7×14.4 in), weighs about 79.83 kg (176 lb) and produces 66.5 dBA at 3 m.

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Document types

How to read your Cummins/Onan serial & model number →

Specifications

Fuelgasoline
Frequency50.0 Hz
Prime power4 kW
Voltage options120 V
PhaseSingle
Rated current33.3 A
Power factor1
Battery voltage12 V
Battery quantity1
Dimensions (L×W×H)762×500×365 mm
Dry weight79 kg
Sound level66.5 dBA @ 3 m

Filters & service parts

model family
ItemSpecCapacityPart #Interval
Air filter— find
Fuel filter— find
Oil filter— find
Belt— find
Coolant—
Oil4.0 quarts—30 hr

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

Common questions

What fuel does the Cummins/Onan QG 4000 use?

The Cummins/Onan QG 4000 runs on gasoline.

Troubleshooting

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Symptoms & remedies

SymptomCauseRemedy
Crank but won’t start1. Fuel below generator pickup level in tank. 2. Fuel supply shutoff valve closed. 3. Carbon deposits on spark plug(s). 4. Low oil level.
Exhausting black smoke1. Dirty air filter. 2. Choke stuck or misadjusted.
Unit runs then stops, or stops when driving around a corner1. Low fuel level. 2. Low oil level. 3. Excess oil.
Unit starts and runs, then stops when the start switch is released1. Low fluid levels. 2. Possible overheating. 3. Other functional problem.
Unit runs then surges1. Loose or worn spark plug leads. 2. Defective ignition coil, wiring, or control components. 3. Faulty spark plug. 4. Governor out of adjustment. 5. Combustion air pre-heat malfunction. 6. Carburetor icing. 7. Carburetor varnishing.
Circuit breaker trips1. Overloaded circuit.
No electric output1. Tripped circuit breaker. 2. Other function problem.
Fails To CrankLow battery.Check battery fluid level and charge or replace the battery if necessary.

Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.

Fuel consumption

RatingLoadL/hgal/h
Half load
Prime
Standby
Standby50%2.270.6
Standby100%3.410.9

Available documents

Spec sheetReferenceOwner's manualService manual