Onan 400 gas generator

[Notsoaverageguy]

So I have a Onan 400 generator in my older motorhome that I am selling, its in a 1996 fleetwood Jamboree. We have owned it for 7 years and it has been somewhat tempermental. I will explain, besides the yearly cleaning out the carb when you start it up its hit or miss whether it will stay running and does not always put out A/C. So if I go to start it and with my finger on the start button if the Tachometer starts clicking away I know everything is fine and the microwave beeps to life. But if the tach doesnt click away and the microwave doesnt come to life it will quite the second I take my finger off the start button. With my finger on the button it will run as long as I keep it on the start button. Whats up?

 

[Kevin D Pem]

Check the 12v relay in the generator compartment

 

[Notsoaverageguy]

Check the 12v relay in the generator compartment

Yeah I went down this road a couple of years ago and replaced it. BUT at your request I checked it. No voltage to either of the big terminals till I start it then Volts on both sides.

 

[Kevin D Pem]

Not the starter relay. There is a relay that is used to maintain the momentary switch state for coil voltage. That is what makes multiple start switches a possibility. It looks like the relay used on older car headlight relays.

 

[Kevin D Pem]

Readily available at any Auto parts store.

 

[TheLooks]

Also, holding the button in bypasses the multiple reasons it will not run. Onan's have a million sensors that shut it down and pushing the button and reading the flashes tell you the code. Google it. It shuts down as soon as you release it because the code is set until fixed.

 

[Notsoaverageguy]

So again I went down this road before, yes the relay in the generator compartment for the 2 switches is what I was talking about. And I know the reason it won’t stay running as I have said this is not new. Before if I was in the coach looking at the Hobbs meter while starting the generator if the meter did not immediately come on I knew it was not going to stay running and kept my finger on the button and usually (sometimes 20-30seconds) would turn the Hobbs meter on and the microwave would beep. First time in 7 years now it just seems dead. Tried resetting the breaker no dice. Steak sauce says that it probably is the brushes or slip rings, but could be the control board. I was hoping that maybe someone here had a easy “try this”

 

[TheLooks]

Sure, since you didn't say that at first, you got the standard replies. Mine is usually what Cummins says. Get a new generator. But what you were doing waiting 20 or 30 seconds was keeping it running until the transfer switch kicked it in and that put a load on it which brought the frequency back into range or rpm's, which effect frequency. It needs to be service by a professional.