6 year old 4kw Onan generator question

I recently bought a used 2013 RV with an Onan 4KYFA26100M generator in it. It had 42 hours on it and had been in storage for a while. The salesman at the dealership had said they always change the oil in a gen after a sale. During the pre-purchase walk through, the generator worked fine, started right up and ran smoothly a couple of times.  It ran long enough for me to test the circuits, probably 5 min. When we finally got the RV back to Massachusetts, I went to run it and the generator no longer worked. It would run until I let go of the start switch and an internet search suggested that I check the oil level as that is a common cause of that symptom.  When I unscrewed  the dipstick, oil came flowing out.  It was way way above the full level on the dipstick, at the very top of the reservoir.  In fact when I siphoned oil out I got well over 200 cc, over 7 oz. extra oil before it was down far enough to read full on the dipstick.  Finally in desperation I changed the oil and here is the really interesting part.  The oil by the dipstick was fresh, clear, new oil.  The oil that flowed out of the drain plug was old, black oil.  The black oil flowed out until the very end when the oil started looking clearer momentarily.  The only scenario I can think of is the tech opened the reservoir and just poured fresh oil in to make it appear that the oil had been changed. The generator hasn't started since. I believe it must have happened after we tested it at the dealership and before we took possession of it and drove it off the lot.  Looking back on our dealings with these people I believe they would be capable of that.

QUESTION:  Am I correct in assuming this model generator never would have run for so long with so much extra oil in it?  I am assuming not  because one of the first things it does is check the oil pressure/level and it will not start if that isn't correct. 7 extra oz. is way out of specs.

Also anyone know of a reputable Onan repair facility in Massachusetts?  I am looking for someone who can diagnose the issue and not just replace parts until it starts working.

Thanks

Most later model Onan 4000 generators do not have an oil level switch in them, unlike the larger 5600 models.  Shutdown upon releasing the start switch is often due to the generator not generating electricity.

Is it still starting but only running as long as you hold the switch in?

NY_Dutch said:

Is it still starting but only running as long as you hold the switch in?

Click to expand...

Yes it only runs until I release the switch

Isaac-1 said:

Most later model Onan 4000 generators do not have an oil level switch in them, unlike the larger 5600 models.  Shutdown upon releasing the start switch is often due to the generator not generating electricity.

Click to expand...

This generator was probably made in 2012.  Is that what you would consider to be a later model?

You may find this Onan troubleshooting guide useful:

http://www.flightsystems.com/pdf/onan-rv-troubleshooting-guide.pdf

Are you plugged into shore power (an electric outlet)?
If so unplug and try again

Welcome to The RV Forum!

Here's a link to the Owners Manual for your generator, in case you don't have it:

https://power.cummins.com/sites/default/files/literature/rv/F-1123-EN.pdf

Does your generator have a light in the switch? If so, you should get a series of flashes when it shuts down which corresponds to one of the Fault Codes on Page 31.

Onan needs to see voltage from the generator and a signal from the Oil Level (not pressure) switch to keep running when you release the Start switch.  It's possible the high oil level damaged the Oil Level switch and it's not working any more, making the control circuit think the engine is low on oil.

Here's another link to your generator's Service Manual.  Troubleshooting starts in Section 6. "Engine Starts But Stops When Switch Is Released" is on Page 6-11.

https://b190.com/files/Onan-Cummins%20RV%20Gen.%20service%20manual.pdf

Year,  make and model of your RV would help us.

If you have a class C or A the fuel for the generator comes out of the gas tank and if the gas tank level is below a 1/4 tank it will shut off the generator.

How much gas is in your gas tank?

How level was the RV when you checked the oil? It needs to be as level as you can get it.