Onan 4000 just shuts down on load No tripped breakers

howardwheeler wrote:
We've checked what we know and find nothing amiss that's obvious. But if we have the microwave and a 1200 watt hair dryer going and the AC kicks on, the generator just stops. But no circuit breakers ever trip. I find nothing in the manual that says the generator just shuts down by itself if 20 to 25 amps are being drawn. I wonder if a fuel filter could be constricted just enough that when the governor calls for full throttle, it starves for gas. Do you think that's a possibility?

1200 watts hair dryer
1200 watts microwave input or more
1800 watts AC start up draw or more
4200 or more watts???

Its a possibility. It has circuitry that turns it off if it cant keep the frequency and/or voltage in spec.

A breaker will trip only when amperage has been exceeded. Your genset cant make enough amps to get there.

Could be carb, fuel supply, dirty air cleaner or a bad controller or connection somewhere.

We've checked what we know and find nothing amiss that's obvious. But if we have the microwave and a 1200 watt hair dryer going and the AC kicks on, the generator just stops. But no circuit breakers ever trip. I find nothing in the manual that says the generator just shuts down by itself if 20 to 25 amps are being drawn. I wonder if a fuel filter could be constricted just enough that when the governor calls for full throttle, it starves for gas. Do you think that's a possibility?

Oil is good. And if we turn off some additional appliance, it always immediately starts right back up, so it's not the oil sensor. It doesn't seem to really bog down but rather just gives up. And I am fairly certain it is tied to drawing higher amps than just the load of a single AC. So my question is, is there a mechanism that shuts down the generator if it senses more amp draw than it wants to give even though no breakers are ever thrown? I'm not talking about more than a thirty amp draw but really only in the low twenties.

Does it bog down and die, or just shut off?

They have a low oil sensor that can shut it down. These have been known to shut down intermittently. Cheap to replace.

They also shut down if the voltage is too high or low. If the carb is dirty and it cant make the HP to maintain voltage it will shut down.

I had one that would shut down while driving if I hit a bump or made a hard right turn. Turns out it had a loose carb nut.

Yours also has an electric fuel pump. They fail too.