Underspeed
Generac
Engine RPM below required frequency
Generator runs sluggishly, may stall under load, and controller displays 'Underspeed' or 'RPM Sense Loss'.
Advertisements
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.
Advertisements
Possible Causes
Insufficient fuel pressure, Clogged fuel filter, Weak governor spring or misadjusted governor, Failing engine speed sensor
How to Fix / Troubleshooting
Safety: Isolate the generator from the load. Do not operate for extended periods at low frequency, as it can damage connected equipment.
- Check fuel supply and pressure: For NG/LP units, verify gas pressure at the generator inlet while running. Ensure the gas meter and regulators are sized correctly. For LP, check for icing at the regulator.
- Inspect fuel filter: Locate the in-line fuel filter and replace it if it appears dirty or has not been changed per maintenance schedule.
- Adjust governor: Inspect the mechanical governor linkage and springs. If the governor arm does not respond to load changes, adjust per the service manual or replace worn springs.
- Test speed sensor: Check the engine speed sensor wiring and connector. Replace the sensor if RPM readings are erratic or lost intermittently.
Advertisements
Repair Difficulty
Medium
3/5
Advertisements