Onan
No Start – Fuel or Ignition Failure
Generator cranks normally but does not fire or start, no specific code shown
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Closed fuel shutoff valve or empty tank, Air in diesel fuel system, Failed ignition coil or spark plug (gas units), Clogged carburetor or injectors
How to Fix / Troubleshooting
Safety first: Disable auto-start. Avoid prolonged cranking to prevent starter damage. Ensure good ventilation to avoid fuel vapor buildup.
- Confirm fuel supply: Check tank level and verify all fuel valves are open. For LP/natural gas, confirm gas supply and pressure.
- Prime fuel system: On diesel units, use the manual priming pump or bleed screws to remove air from the fuel lines until fuel flows without bubbles.
- Inspect ignition (gas): Remove spark plugs, inspect for fouling, and replace if worn. Check ignition coil connections and test for spark using a spark tester.
- Carburetor/injector cleaning: If the unit has sat for a long time, varnish may clog the carburetor jets or injectors. Use fuel system cleaner or have the components professionally cleaned.
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Repair Difficulty
Medium
3/5
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