What surging looks and sounds like
A surging generator sounds like it's revving up and down on its own, often rhythmically. Lights may flicker in time with the engine. It can happen with no load, under light load, or only when something big like an air conditioner turns on.
Fuel delivery is the usual suspect
Generators rely on a steady fuel supply to hold a constant speed. A partially clogged carburetor jet, a dirty fuel filter, or varnish from old fuel can starve the engine just enough that the governor keeps chasing the right speed. That chasing is the surge you hear.
Other possible causes
- A dirty or restricted air filter
- A vacuum or intake leak
- Governor linkage that is sticking, bent, or out of adjustment
- Running at high altitude with settings meant for lower elevation
- Overloading the generator beyond its rated output
Why it matters
Unstable engine speed means unstable voltage and frequency. Sensitive electronics, RV converters, and appliances don't love that. If your generator is surging, it's worth unplugging sensitive devices until it's sorted out.
Getting help
Note when the surging happens (no load, light load, heavy load) and whether it started after the generator sat for a while. That detail helps narrow things down quickly.