Generator Surging or Running Rough Under Load
A generator that surges — revving up and down at idle or under load — is telling you something is wrong with fuel delivery or engine speed control. This matters more than it might seem: a surging generator produces unstable power output that can damage sensitive electronics and appliances. It also indicates a problem that will likely get worse, not better, under continued use.
Common Symptoms
- Engine revs up and down rhythmically at idle
- Engine surges when a load is connected
- Output voltage fluctuates — lights flicker when connected
- Generator runs fine at first but surges after warming up
- Generator dies under moderate load
Likely Causes
- Carburetor pilot circuit clogged — most common cause of surging
- Dirty or partially blocked main jet
- Carburetor governor spring worn or misadjusted
- Air filter clogged — restricting airflow at load
- Old or water-contaminated fuel
- Engine running lean from an air leak at the intake gasket
What We Inspect
- Carburetor — pilot jet, main jet, and emulsion tubes
- Governor spring and linkage for wear or improper adjustment
- Air filter condition
- Fuel freshness and water contamination
- Intake manifold and carb gasket for air leaks
- Output voltage stability under load
Professional Diagnosis
Governor adjustment on a generator engine requires specific knowledge of the correct RPM range (typically 3600 RPM for 60 Hz output). An incorrect governor setting produces the wrong frequency and damages connected equipment. We service generators to spec so your output is stable and within range.
Related service: Generator Repair