Symptoms
- Engine speed rises and falls rhythmically on its own
- Lights connected to the generator flicker with the surging
- Idle speed hunts up and down at rest
- Surging worsens the longer it runs
Likely causes
- CommonDirty carburetor with partially clogged jetsRestricted fuel flow causes the engine to hunt for the right mixture, producing rhythmic surging.
- CommonGovernor linkage loose or out of adjustmentThe governor controls engine speed to maintain steady output frequency; a loose or worn linkage causes hunting.
- PossibleAir leak in the intake or carburetor gasketUnmetered air entering the engine confuses the fuel mixture and causes surging.
- PossibleOld or contaminated fuelWater or debris in the fuel can cause inconsistent combustion.
- PossibleClogged fuel filter or fuel line restrictionPartial fuel starvation causes the engine to surge as it searches for a stable speed.
What to do
- Stop using sensitive electronics on the generator while surging occurs, since fluctuating voltage/frequency can damage them.
- Check the fuel for contamination or age; drain and replace with fresh gasoline if it's been sitting.
- Inspect the governor linkage (usually a small arm and spring near the carburetor) for looseness or disconnection, and reconnect or tighten as needed.
- Check for visible air leaks at the carburetor gasket or intake boot.
- Replace the inline fuel filter if the generator has one and it looks dirty.
- Clean the carburetor's external adjustable jets if accessible, or use a carburetor cleaner spray through the intake per the manual.
- If surging continues after fuel and governor checks, a small-engine shop can clean the carburetor fully or adjust the governor properly.
Tools and parts
- Screwdriver set
- Fresh gasoline
Generator fuel filterSearch: “generator inline fuel filter”
Carburetor rebuild kitSearch: “small engine generator carburetor rebuild kit”
When to call a pro
Persistent surging that risks damaging connected electronics should be diagnosed by a small-engine repair shop rather than run through repeatedly.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.