Onan 4.0 starts and shuts off immediately

Skip 500 · 06-17-2019, 05:28 PM

Finally, we picked up our motorhome from the body shop after 5 months. Unfortunately the generator was not run during this time. Tried starting, would not start, drained bowl of carb, starts and shuts off immediately. first code flashes 3, pushed stop to get other code, flashes 36. All this stands for is engine shut off. Any ideas?

Judge · 06-17-2019, 06:41 PM

Starting with the basics...... is your fuel level over 1/4 tank? It is designed ot shut off when the fuel reaches 1/4 tank or less.

If you do have enough fuel, it could be an issue with the fuel level sensor shutting it off if it thinks there is not enough fuel.

Skip 500 · 06-17-2019, 06:51 PM

Fuel tank is 3/4 full, Oil level is almost to the top off the full mark and checked on a level surface

Pete'sMH · 06-17-2019, 09:34 PM

Fuel, air and spark...usually its fuel. After it shuts off check the float bowl. If it’s still full the pump and lines are probably working. It it’s not then it’s just burning off the bowl but having trouble staying full. If the fuel filter is dirty it may be allowing enough fuel to flow to fill the bowl on the starter but not enough to keep up with a running engine. Check the float valve and jets and also the air filter. Best of luck.

**EA37TS** · 06-17-2019, 10:02 PM

You don't say how old the coach or generator are. A few years ago Onan had some fuel pump diaphragm problems. Had the problem on my prior coach.

Ford1 · 06-17-2019, 10:40 PM

I am inclined to agree with Dave. I had the EXACT same scenario on my last coach and it turned out to be the fuel pump. Easy enough to check. If you can find the fuel line going into the carburetor, disconnect it and get a bucket. Hold the fuel line over the bucket and press the generator start button (on the upper left side of the generator) to the PRIME direction. It should pump fuel freely and with vigor until you release the Prime button. If it pumps a little squirt or two and then dribbles, chances are good that the pump is toast.

Skip 500 · 06-17-2019, 11:57 PM

The generator is only 1 1/2 years old and only has 11 hours on it.

Pete'sMH · 06-18-2019, 02:34 AM

Quote:

Originally Posted by Skip 500

The generator is only 1 1/2 years old and only has 11 hours on it.

That’s a clue....Onan says to run the generator under 50% load for (I think) an hour a month. Unless that’s all it’s been doing it might have sat. Fuel can turn sort of gummy in as little as 30 days so perhaps stagnant fuel in the carb has clogged you up some. Might have to have the carb cleaned or at least try some cleaner through the jets. Still, couldn’t hurt to check the flow from the pump as suggested. The fact that it starts suggests that your spark is ok and at 11 hours your air filter will be pristine.

Judge · 06-18-2019, 09:18 AM

My rig is a year old and I have only run my generator about 15 minutes a month and it fires right up every time.

You mention in your original post that your rig was in the body shop. I would be checking the wiring going into the generator and then work your way back.

There could be a wire that got damaged / shorted and a sensor is sending a false message.

There is a sensor for not enough fuel in the tank so it shuts down and there is also a low oil pressure sensor.

You can try pulling the wire from the oil pressure sensor to see if that lets it run. If it does, replace the sensor.

**EA37TS** · 06-18-2019, 01:05 PM

Another thought. If you registered the Onan warranty with Onan call and talk to them. They will tell you where to start looking. Keep in mind the generator warranty is separate from the coach warranty.

Skip 500 · 06-19-2019, 03:08 PM

Thanks for all of the replies. Right now the rv is at the dealer getting some warranty repairs and as soon as I get it back I will contact my local Onan repair shop.

apr67 · 07-01-2019, 04:12 PM

Error 36 is telling you the generator didn't turn itself off, which means it wasn't hot, low on oil or other issues. It often means a fuel delivery problem.

The Gritz Carlton · 07-01-2019, 05:10 PM

Check oil level...this seems to be a common issue...probably "high oil level" shutoff...

https://www.youtube.com/watch?v=vzXDlln8aUw

Skip 500 · 07-01-2019, 06:49 PM

Thanks Gritz, I am not getting an oil code, just the engine shut off code which apr67 said is a fuel delivery issue. I Think????

The Gritz Carlton · 07-01-2019, 07:00 PM

According to the video and what others have said about this specific issue, Code 3-6 is pretty generic. This guy seems to think there's a common problem with the dipstick reading incorrectly, allowing an overfill of the crankcase, causing random shut downs.

apr67 · 07-01-2019, 07:02 PM

Quote:

Originally Posted by Skip 500

Thanks Gritz, I am not getting an oil code, just the engine shut off code which apr67 said is a fuel delivery issue. I Think????

Well 36 just means the generator shut down, and the control board and or control panel didn't do it. It doesn't always mean fuel (but often it does).

The oil over fill issue on the 4k seems pretty common and it looks like it would be an easy test.

I can not find anything on why being over filled would shut the generator down, but in cars being over filled can cause the rotating mass to hit the oil, aerate it and cause low oil pressure. Could be a similar mechanism? If so I would expect however a low oil pressure code.

Could also be that in an over full condition the oil expands and that causes some sort of issue where the drag causes the engine to quit, I just don't have any idea.

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