Cummins Onan 4000KW Generator

[Luke D]

My question is on why engine won’t stay running. Cummins in Tampa is telling me the Stator or Rotor on the Generator is showing a dead short. Okay??? So why does this kill engine ignition was my thought. They also tell me it’s a common problem as parts are brittle. Gen has less than 350 hours. Crazy. So in my second season , in my first Motorhome, Thor ACE 30.1. The only bad issue has been the Onan generator. I find it hard to believe Cummins Onan would build poor reliable equipment. Guess my 4000KW is a rarity. Anyone experienced Onan reliability issues?

[bjones3211]

On my old RV I have a similar issue with my generator and when I found out unless you have a real good meter you can’t really test a resistance him in the coil‘s or mine ended up being was a voltage regulator
When you say it won’t stay running how long does it actually run

[Luke D]

Originally Posted by bjones3211

On my old RV I have a similar issue with my generator and when I found out unless you have a real good meter you can’t really test a resistance him in the coil‘s or mine ended up being was a voltage regulator
When you say it won’t stay running how long does it actually run

It fires for only a second. If you spray into carburetor maybe a little longer but it wouldn’t run. Replaced, carb, control board, (which is voltage regulator) fuel pump, and filter. Tank is full. I have checked voltage on fuel solenoid and have none. Cranks fine. Cummins Onan says rotor or stator is a dead short. Generator is there now. I couldn’t find a short or bad circuit with my fluke meter

[bjones3211]

OK the reason I asked how long will it run before it shut off is the generator will switch over from battery for your coils to its own power as soon as you let go of the start button if it dies soon as you let go of the start button you know that for some reason the system is not producing the voltage to keep the engine running I tried to find a website that I use but it was several years ago so I couldn’t find it but I do know there’s quite a few places that you can go for a troubleshooting that might help you

[Bob Denman]

Luke,
I think that since Cummins said what the problem was: do you believe them?
And are they fixing it?

[16ACE27]

This is not the first I have heard of a shorted stator. Usually due to corrosion. Were you doing your monthly maintenance runs?

If the generator's control board does not see frequency and voltage in specs it will shut down and give you a code as to why it shut down.

Did you research the codes you got when it shut down?

[Luke D]

Originally Posted by bjones3211

OK the reason I asked how long will it run before it shut off is the generator will switch over from battery for your coils to its own power as soon as you let go of the start button if it dies soon as you let go of the start button you know that for some reason the system is not producing the voltage to keep the engine running I tried to find a website that I use but it was several years ago so I couldn’t find it but I do know there’s quite a few places that you can go for a troubleshooting that might help you

Thanks , I have no doubt no voltage is being produced once finger is removed from switch. Only hope I find a solution. I am very maintenance minded, and always maintain everything on my RV and personal vehicles and equipment. Just very disappointed with a totally unreliable piece of equipment

[Luke D]

Originally Posted by Bob Denman

Luke,

I think that since Cummins said what the problem was: do you believe them?

And are they fixing it?

Hi Bob , hope all is well. Not sure what to believe. My original RV repair people ( Boondockers RV Service) has been trying to make the unit run for over two months. They sent the generator to Cummins Onan in Tampa. My RV sets generator less. Of course the only good about this is it’s entirely under warranty. Still need the fix or solution.

[Bob Denman]

I hope that they get it together for you soon!
Stators........

[Luke D]

Originally Posted by 16ACE27

This is not the first I have heard of a shorted stator. Usually due to corrosion. Were you doing your monthly maintenance runs?



If the generator's control board does not see frequency and voltage in specs it will shut down and give you a code as to why it shut down.



Did you research the codes you got when it shut down?

Codes where 33 or 34. Totally generic run stop codes. Not pointing to a specific cause. As far as maintenance, I’ve been on top of all aspects of care. I follow , actually over do, recommended requirements. The unit looks like brand new. We are the second owners, but are very happy with all aspect of the Motorhome. It’s like new . Oh well only 343 hours on Generator clock on a 5 year old model. Maybe it is corroded inside. I ran fine for us for 70 something hours.
Thanks
Stay safe

[16ACE27]

Originally Posted by Luke D

Codes where 33 or 34. Totally generic run stop codes. Not pointing to a specific cause. As far as maintenance, I’ve been on top of all aspects of care. I follow , actually over do, recommended requirements. The unit looks like brand new. We are the second owners, but are very happy with all aspect of the Motorhome. It’s like new . Oh well only 343 hours on Generator clock on a 5 year old model. Maybe it is corroded inside. I ran fine for us for 70 something hours.
Thanks
Stay safe

Well the maintenance of concern is running it with at least 1/2 load monthly for 1 to 2 hours. That's supposed to drive the moisture out of the windings.

[Luke D]

Originally Posted by 16ACE27

Well the maintenance of concern is running it with at least 1/2 load monthly for 1 to 2 hours. That's supposed to drive the moisture out of the windings.

Well, can’t speak for previous owners , only myself. I’ve met an exceeded that. Looking at the hours I guess no way I know what previous owner did as far as monthly run times. Thanks for the info.

Stay safe

[Luke D]

Originally Posted by Luke D

Well, can’t speak for previous owners , only myself. I’ve met an exceeded that. Looking at the hours I guess no way I know what previous owner did as far as monthly run times. Thanks for the info.

Stay safe

UPDATE!!!!!!11/28/2020

Well generator back from Cummins Onan in Tampa Florida an installed. No stator or rotor issue. Cummins found a wiring issue. Wouldn’t elaborate. Not pointing fingers at original RV attempted repair in June. Cummins stated Stator or rotor failure extremely rare. Now everything is new and fires on first crank and purrs like a kitten. A quiet kitten. The only thing I noticed when looking at it , besides how clean it is, was they moved the fuel solenoid ground wire to a different spot directly on engine base. Book shows it there so who knows if this was the issue. Wire was on tray under carburetor.
Thanks Cummins.

[16ACE27]

Great! Glad you got it resolved.

[Bob Denman]

Glad to read that you're back in business!

[TripleGGG]

Always good to read of positive outcomes.