Onan 4000 with shut down but will restart
 

This past weekend i had my 2018 motor coach Onan 4000 generator intermittently shut down when the A/C was on sometimes it would run for a couple of hours and then shut down, other times it could run for 15 minutes and then shut down. Each and every time the generator would restart with no problems. Prior to the generator shutting down it sounded as if was under a heavy load. If I was quick enough to get into the coach and turn the A/C off I was able to keep the generator running. Any ideas where to begin?

Re: Onan 4000 with shut down but will restart
 

I would get a frequency meter and check to see the generator freq output. Make sure it's within 58-62 HZ. I'd bet it was low. It's HOT outside. Like our race cars we don't make the same HP in the summer as we do when it's cooler. This can be adjusted by raising the engine RPM.
Dan

Re: Onan 4000 with shut down but will restart
 

Mine was wiring going to air conditioner. I started looking when I had the same problem it was where they wire nutted a couple of cables in coach basement. I was getting red hot and Im guessing drawing way to much amperage. Made repair and problem went away

Re: Onan 4000 with shut down but will restart
 

Thanks I will check the frequency and check the wiring harness

Re: Onan 4000 with shut down but will restart
 

Make sure the oil is not too full. It can be in the middle of the dipstick good area.

Most of the new machines are set a touch lean on the carbs mixture. For best CO Emissions....

You could try richening it up 1/2 a turn, out..

The black plastic cap on the carb is a tamper proof item that prevents you from backing that mixture screw out past where it was set at the factory. It allows just a small amount of change for altitude....leaner....

The black plastic cap is knurled and so is the mixture screw. It just presses on. You can very carefully with a bent screwdriver pry that cap off. Carefully because the mixture screw is brass and can be broken. It's a needle inside....

Richen it 1/2 a turn out from it's most rich setting and see if it helps.....You can always put it back to where it was. You don't have to put the black plastic cap back on but I usually do...

The machine must have the service door in place and they run best with good airflow to keep them as cool as possible. Some MH installs are not good for that issue. Not enough cool air able to be pulled in that service door opening sometimes......To close to outer door and no louvers in that door. They get hot and it affects fuel system.....

I own 2 of them and occasionally have similar problems.....They get to hot and may shut down.....and being lean does not help....

Re: Onan 4000 with shut down but will restart
 

High resistance builds heat and creates problems as you found...

Plastic wire nuts melt from the heat of a poor connection and it gets worse and starts arcing.....It's a common problem I see pretty often......

Re: Onan 4000 with shut down but will restart
 

Thanks Rich , you may be on to something with the oil level, I just recently had it serviced at Camping World, prior to that I had no issues with it shutting down. I'll check it out later today and post my findings.
thanks

Re: Onan 4000 with shut down but will restart
 

just got back from checking the generator out. The oil level is at top of the full line. I will change the oil and lower the level. everything else looks ok.
thanks