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CMac455 · 05-05-2015, 02:17 PM

I fully rebuilt the generator motor and had it running for some time. Now the generator has started to shut off as soon as it starts up. We took it to a Cummins shop and they said that the stator is bad and we need a new one. I'm not sure how true that is, but does anyone have any troubleshooting guides?

If I were to take their advice, where could I find a stator and a manual for replacing it?

Thanks

Full.Monte · 05-06-2015, 07:51 AM

Do you have more than 1/3 tank of gas in it? If not, it may be sucking air. Most motor homes have a safety feature built in that keeps you from running out of fuel by using the generator. They do this by pulling fuel from the tank at a higher level than the fuel pump for the engine does. Since you didn't say what rig you have or whether it is diesel or gas, it's hard to conjecture too much. I suggest you put these pieces of info in your signature so it's always there.

garyspang · 05-06-2015, 11:02 AM

Search for a wiring schematic for the generator. Then with an ohm-meter check the continuity of all windings and shorts to the casing (ground). I had to replace the brushes on the rotor after a trip to Alaska. The fine dust so prevalent on their side roads and the Casiar ground down the brushes. All the cooling air goes past the brushes. The generator behaved just like yours.
The stator is a heavy and expensive assembly. So check it thoroughly before forking out a lot of money to fix it.

deandec · 05-07-2015, 11:39 AM

http://cdn.shopify.com/s/files/1/006...NUAL_1.pdf?376

There are trouble shooting steps for both engine and power generation in the manual at the link.

superk · 05-07-2015, 06:16 PM

The newer Onan generators will power down if, for some reason, they are not producing power.

They will also shut down in a few other conditions.

I would recommend first checking the easy stuff. Check your brushes, and your slip rings. If they are dirty (should be very bright and shiny copper) your voltage regulator has to work overtime to produce power across the rings. This may overload the regulator and if this happens too often, it could be fatal to the regulator itself.

I had mine do similar.

These dirty slip rings killed my voltage regulator. This pic is after I partially cleaned them too!! It was a very unfortunate and ($270) error.

Test the easy stuff first!!

CMac455 · 05-08-2015, 06:20 AM

The Motorhome is a 1998 Winnebago 454 Chevy gas engine. The generator is the Emerald Plus Onan just like the one in the picture below. I do not have a model number, unfortunately, but I will try to get it.

Where would I find a wiring diagram or troubleshooting guide? You guys think I should do a resistance check of all of the wires that go to the stator?

Would the "slip rings" and "brushes" be accessible through disassembling the electricity generator portion from the engine or would be be serviceable while it's installed?

This would be the first time i've ever messed with a generator's electrical unit. Would someone be able to provide a list of things to check and I can identify/access these components?

Thank you all very much for your help!!

wa8yxm · 05-08-2015, 06:47 AM

I assume it is an ONAN.. ONAN generators check up on themslves and one of the things they test is the 120vac output.. IF it is not there, they shut down soon as you let loose the start button and flash the code for "Cranking speed too low" (Thankfully I learned this the cheap way... NOT MY GENERATOR).

Strator is one of the things that can cause no AC out.. Mike had bad brushes on his.. But the job of replacing the strator is about 5 MINUTES longer than replacing the brushes. (Well perhaps 15 minutes longr) so if The manufacturer's shop says Bad Strator.. I would tend to believe them.