Generator runs only while holding start button

[inacioface]

As stated in the subject line, my ONAN 4000 generator will start and continue running only while holding the start button down. Once I let go of the start button, the generator turns itself off. Any ideas of what might be causing this? I've learned that the generator will not turn on if the gas tank has less than 1/4 tank of gas, but that is not the issue here since I have much more than a 1/4 tank of gas and the generator has no trouble starting.

Any help would be greatly appreciated. Thanks!

[chin_k]

When you say it runs when holding down the button, is it really running, or merely cranking by the electric starter?

I suggest you take a look at the service manual and see if you can follow the troubleshooting steps in the document. If it is electrical issue, it can be the controller. For my rig, I need to have at least 1/3 tank for the generator to run.

[inacioface]

It was definitely running.

I checked the oil level by removing the oil filler cap/dip stick (I believe they are the same thing) and oil started pouring out of the inlet. I quickly put twisted the filler cap by on. I then disconnected and reconnected the remote starter (I read online that sometimes the connections need to be reseated) and after doing those two things it doesn't even crank anymore... I think I opened a can of worms .

I'm going to read through the service manual as suggested here and while I'm at it, I'll order a new remote start with an hour meter (which mine is missing).

[sm350bl]

There should be three locations where you can start the generator. one in the overhead control panel for driver, one by the closet and one in the generator compartment. Do you get the same problem at all three locations? Might help you rule out the coach vs something localized at the generator or vise versa.

[chin_k]

Yeah, I would do the local panel to start the genset before getting a new remote switch. The fact that the genset does not stay running does not seem to be related to the switch.

[SMan]

FWIW
I have had a few RV's with the Onan Genset. They have all had issues a lot of them resulting from not "exercising" the genset under load on a regular basis. (Why my Honda 6500 home genset never has an issue even after not being used for extended periods puzzles me.) In each case a carb replacement has solved my starting issues. (They are pretty easy to change and after Onan charging a small fortune to do one I do my own installs)

In my current Chinook I installed a new carb some years back but have again neglected to exercise it as I should. Now when it doesn't want to start with the remote buttons I go to the genset itself and use the start button there along with holding it in the prime position for 5 or so seconds. It will usually fire. If not I rotate the "Altitude" adjusting nob on the carb back and forth a few times and it has never failed to start.

These are just my experiences and yours may vary.

[JabberBox]

https://www.rverscorner.com/onan.html

[inacioface]

There should be three locations where you can start the generator. one in the overhead control panel for driver, one by the closet and one in the generator compartment. Do you get the same problem at all three locations? Might help you rule out the coach vs something localized at the generator or vise versa.

I've attempted to start the generator for all three locations, but still no luck. As mentioned previously, the generator would start only willing holding the button down, but after removing and reinstalling the dip stick and disconnecting and reconnecting some wire harnesses, the generator doesn't crank over anymore.

Yeah, I would do the local panel to start the genset before getting a new remote switch. The fact that the genset does not stay running does not seem to be related to the switch.

It would never start even when presses the local start switch. After trying to debug it myself, it doesn't crank over anymore.

FWIW
I have had a few RV's with the Onan Genset. They have all had issues a lot of them resulting from not "exercising" the genset under load on a regular basis. (Why my Honda 6500 home genset never has an issue even after not being used for extended periods puzzles me.) In each case a carb replacement has solved my starting issues. (They are pretty easy to change and after Onan charging a small fortune to do one I do my own installs)

In my current Chinook I installed a new carb some years back but have again neglected to exercise it as I should. Now when it doesn't want to start with the remote buttons I go to the genset itself and use the start button there along with holding it in the prime position for 5 or so seconds. It will usually fire. If not I rotate the "Altitude" adjusting nob on the carb back and forth a few times and it has never failed to start.

These are just my experiences and yours may vary.

I will rotate the altitude knob when I get home today and see if that gets it going. I'll also look into replacing the carb myself.

https://www.rverscorner.com/onan.html

Thanks for this link. I'll see if I can debug this myself and I'll let you know what I find/attempt to do.

[inacioface]

Is the generator typically connected to the coach battery bank or the starting battery under the hood?

[caconcourse]

In my 2001 Concourse, the generator is connected to the coach batteries, with a 50 amp breaker inside the generator compartment. I've read about other (older?) models that connected the generator to the truck battery with a 50 amp breaker under the hood near the firewall.