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Generator surges up and down under no load after sitting all winter Fuel System
Small 3kW generator. Starts fine, but with nothing plugged in it hunts, revving up and dropping roughly once a second. Put a 1kW heater on it and it steadies out completely. It ran fine last autumn and then sat from November to March with fuel in it. Is a surging engine always the carburettor?
@weekend_margin · 7mo ago · 3 replies
Almost always, and specifically the idle circuit rather than the main jet. Under load the engine draws through the main jet and everything is fine, which is exactly what you are seeing. At no load it is running on the pilot circuit, and that passage is far smaller and blocks far more easily.
Pull the bowl, remove the pilot jet if yours is removable, and clean it and the small passages around the throttle plate. On many of these the pilot is pressed in and you clean it in place with cleaner and air.
The other candidate is the governor. If cleaning does not settle it, check the linkage for slop and the spring for being stretched or hooked in the wrong hole - a worn linkage hunts because the governor overshoots both ways. But do the carburettor first, given the winter sit.
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@probe_to_ground · 7mo ago
Pilot circuit versus main jet, decided by load, is a clean diagnostic. Straight into my notes.
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@weekend_margin · 7mo ago
Load tells you which circuit it is running on. It is the most useful free test on any small engine.
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