Underspeed
Kohler
Engine Speed Below Minimum Threshold
Controller displays “Underspeed” shortly after start; engine may stall or run roughly at low RPM.
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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
Fuel starvation or low gas pressure, Governor actuator weakness, Binding throttle linkage, Faulty speed sensor
How to Fix / Troubleshooting
Safety first: Turn generator OFF, open main breaker, and close gas supply valve before working on fuel system.
- Fuel supply: Confirm adequate gas pressure and open valves. Inspect for kinks or damage in flexible fuel lines.
- Air filter: Replace a dirty air filter that may be restricting airflow.
- Throttle and governor: Inspect and free up any binding in the throttle linkage. Ensure the governor actuator moves smoothly when commanded (you may hear or feel it during start attempts).
- Speed sensor: On some models, a magnetic pickup or crank sensor provides speed feedback. Inspect its connector and wiring for damage.
If the engine cannot maintain speed under light load, a professional should test fuel pressure, governor output, and sensor signals.
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Repair Difficulty
Hard
4/5
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