Onan 4000 generator runs rough under a load
My Onan gas generator runs very rough (surges) when I put it under a load like using the microwave or air conditioner, etc... I figured the fuel line must be restricted. I tried adding some sea...
Forum Discussion
First, check the obvious like the fuel and air filters.
But the most likely culprit is dirty jets in the carburetor, caused by not running the generator frequently enough. The solution is to replace or rebuild the carb.
You might find this thread interesting:
https://www.smokstak.com/forum/showthread.php?t=181300
That forum in particular is very good - it has links to the service manuals for your generator that includes detailed diagnostic and repair procedures, far beyond what is in the usual customer manuals.
Since your genny has probably been not getting enough exercise, you might also want to check the resistance between your two brushes. Should be less than 80 Ohms, ideally less than 30. High resistance means you need to clean your slip rings. Flight Systems makes a "Slip Stick" for carefully polishing the rings while the genny is running/cranking. But you can also make your own with a dowel rod and some brown 3M scrubby material glued to it. High slip ring resistance will damage your voltage regulator ($250+).
Seafoam and other "mechanic in a can" solutions probably are not going to help, but it's worth a shot.
But the most likely culprit is dirty jets in the carburetor, caused by not running the generator frequently enough. The solution is to replace or rebuild the carb.
You might find this thread interesting:
https://www.smokstak.com/forum/showthread.php?t=181300
That forum in particular is very good - it has links to the service manuals for your generator that includes detailed diagnostic and repair procedures, far beyond what is in the usual customer manuals.
Since your genny has probably been not getting enough exercise, you might also want to check the resistance between your two brushes. Should be less than 80 Ohms, ideally less than 30. High resistance means you need to clean your slip rings. Flight Systems makes a "Slip Stick" for carefully polishing the rings while the genny is running/cranking. But you can also make your own with a dowel rod and some brown 3M scrubby material glued to it. High slip ring resistance will damage your voltage regulator ($250+).
Seafoam and other "mechanic in a can" solutions probably are not going to help, but it's worth a shot.
