Overcrank
Generac
No ignition / flooding during start
Generator cranks strongly but never fires, strong fuel smell from exhaust, then Overcrank alarm appears.
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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
Fouled spark plugs, Failed ignition coil, Incorrect air–fuel mixture due to clogged air filter, Low compression from engine wear
How to Fix / Troubleshooting
Safety: Turn the generator to OFF and disable the automatic start function. Close the fuel shutoff valve if accessible. Work in a well-ventilated area.
- Inspect spark plugs: Remove all spark plugs. Check for heavy carbon, oil fouling, or cracked insulators. Clean lightly with a wire brush or replace with OEM Generac-specified plugs gapped to the correct specification (see unit manual).
- Check air filter: Remove the air filter element from the air box. If it is heavily soiled or oil-saturated, replace it with a Generac OEM air filter. Do not run the unit without a filter except briefly for testing.
- Test ignition coil: With plugs removed and grounded, crank the engine and check for strong blue spark at each plug. If spark is weak or absent on all cylinders, test the ignition coil primary resistance and wiring harness. Replace the ignition coil/module if out of spec.
- Reassemble and test: Reinstall plugs and air filter, open the fuel valve, set the controller to MANUAL and attempt a start. If the unit starts and runs smoothly, return it to AUTO.
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Repair Difficulty
Medium
3/5
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