Symptoms
- Engine speed rises and falls repeatedly
- Lights or tools plugged in flicker or pulse
- Engine runs rough at idle
- Problem got worse after sitting unused
Likely causes
- CommonDirty or clogged carburetor jetsVarnish from old fuel restricts fuel flow, causing hunting and surging.
- CommonClogged fuel tank ventA blocked vent creates vacuum that starves the engine intermittently.
- CommonStale or contaminated fuelOld gas burns unevenly and causes speed fluctuations.
- PossibleDirty air filterRestricted airflow disrupts the fuel-air mixture.
- Less commonGovernor linkage issueA loose or worn governor can cause erratic speed control.
What to do
- Drain old fuel and refill with fresh gasoline.
- Check the fuel cap vent isn't clogged; some caps have a small vent hole that can get blocked.
- Clean or replace the air filter.
- Let the carburetor bowl drain and refill with fresh fuel if the machine sat for a long period.
- Inspect the governor linkage for looseness or disconnection if visible and accessible.
- Run the generator under a light load to see if surging improves once warmed up.
- If surging continues, the carburetor likely needs professional cleaning or rebuilding.
Tools and parts
- Fresh gasoline
- Replacement air filter
Generator carburetor rebuild kitSearch: “generator carburetor rebuild kit”
When to call a pro
A small-engine shop can clean or rebuild the carburetor and check the governor if fuel fixes don't stop the surging.
Safety
Use caution
Always run generators outdoors in a well-ventilated area away from doors and windows to avoid carbon monoxide poisoning.