Onan generator starts then dies: timing clues and fixes

Dies as soon as START is released

This may involve a start/run control issue, output sensing, low voltage, oil-pressure protection or a model-specific safety input. Check battery voltage during cranking, oil level, generator breaker position and stored fault code. Do not hold the switch to force it to run.

Runs briefly, then slowly fades out

A fade-out often points toward fuel delivery or carburetor restriction. Confirm fuel level above the RV generator pickup, fuel shutoff position, filter condition and whether the generator was stored with old gasoline. A weak fuel pump can also show up after the bowl empties.

Runs until a load is added

Turn off all loads, start the generator and add one load at a time only if the manual allows. Shutdown under load can point to fuel starvation, carburetor trouble, overload, governor response, voltage regulation or a heavy RV appliance with a problem.

Runs hot, then shuts down

Check cooling-air openings, exhaust restriction, enclosure panels, debris, high ambient temperature and whether stored gear is blocking airflow. Never operate with covers removed if those covers direct cooling air.

Related diagnosis pages

• Onan generator code 36
• Fuel pump symptoms
• Carburetor problems
• Low oil shutdown
• Generator troubleshooting guide

Stop-and-call-service signs

Call for service if the generator repeatedly shuts down with a code, leaks fuel or oil, surges violently, produces heavy smoke, trips output protection, smells hot, has exhaust damage or requires internal electrical or fuel-system testing.