Onan
Incorrect Engine Speed / Frequency Out of Spec
Generator runs but frequency (Hz) is too low or too high
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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
Misadjusted governor, Binding throttle linkage, Weak governor actuator, Incorrect fuel mixture causing poor speed control
How to Fix / Troubleshooting
Safety first: Disable auto-start and open the main breaker. Use a frequency meter or multimeter with Hz function.
- Measure frequency: With no load, measure output frequency. Compare to the rated value (typically 50 or 60 Hz).
- Inspect linkage: Ensure throttle and governor linkage move freely. Lubricate pivot points and correct any binding.
- Governor adjustment: Follow the Onan service manual to adjust governor speed and droop settings. Do not over-speed the engine.
- Actuator check: If adjustments do not hold, the governor actuator may be weak and require replacement.
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Repair Difficulty
Hard
4/5
Required Part
Governor Actuator
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