Generac GP1800 GP3250 GP5000 generator idles rough refers to when portable generator runs too slowly while disconnected from a load, causing the engine to run irregular, hesitate or shake.
There are a good number of items that can cause a Generac portable generator to run rough. So we’ve listed a troubleshooting guide that you should follow if the engine idles rough or if the engine starts hard and runs rough.
Follow this checklist if your Generac GP1800 GP3250 or GP500 idles rough.
Engine Starts Hard and Idles Rough
- Check fuel supply. Add fuel if gasoline is low. Ensure the gas is not deteriorated.
- Inspect choke operation and position. Push choke in after starting.
- If choke operation is good, check or test spark. If engine idles rough because of spark issues, test or check flywheel. If flywheel is bad, replace. If flywheel is good, replace magneto.
- If spark is good, check or test spark plug. Check for bad isolations, dirt or if it’s worn. Replace spark plug if needed.
- If the spark plug is good, check carburetor is getting fuel. Check for blockage to passages. Repair or replace as needed.
- If carb is good, test, check or adjust governor and replace if needed.
- If the governor is operating correctly, check valve adjustment. Refer to factory service manual for valve adjustment procedures. Adjust valves and retest.
- If valves meet factory specifications, check engine compression with a compression gauge and do a leak down test.
Repair or replace any parts as necessary. Always refer to the engine service manual when performing service, repair, troubleshooting and maintenance to the generator.
The information herein also applies when the Generac portable generator is surging, revs up and down or surging while under load.