Onan 4kw stops when start button is released

I have a Onan 4BGEFA26101F 4KW Emerald I generator in my 1988 Winnebago Chieftain that stops running as soon as you let go of the start button. I have tried a new control board, but it did not help. I talked to a few people and was told that it could be the voltage regulator. I put a new Flight Systems one and it still won't run. I checked the A.C. voltage at the circuit breaker while holding the start button in and it was around 40VAC. I then cleaned the rotor slip rings and put in a new set of brushes. Still won't stay running. I saw a test that involved removing the voltage regulator and taking a 9V battery and connecting it to the wires of the brushes. The generator will run after I let go of the start button. But the output was around 40VAC. I found in the manual that when the DC voltage to the brushes goes up, the AC output voltage goes up. But even after connecting six 9V batteries in series for a total of 54 VDC, it only went up to 62 VAC. Next I got a set of wiring diagrams and a manual and I checked the rotor with a meter and got 21.9 ohms. The manual said it should be 21.8 ohms so I figured it is good. Next I pulled out the stator and got the following readings:

T1-T2 was .9 ohms, the manual said it should be .330 ohms +/- 10%
T3-T4 was .9 ohms, the manual said it should be .330 ohms +/- 10%
Q1-Q2 was 1.2 ohms, the manual said it should be 3.47 ohms +/- 10%

Does anybody know if this indicates a bad stator? And if it is bad, does anybody have any suggestions on where to get on at a reasonable price? Going by the manual, it says it is part number 220-4135-04.
Thanks in advance for the help!
Greg

I"m not sure what it means (Bad Strator is one possible meaning) but I suspect a visit to your local ONAN service center or Cummins service center is high on the list of things you shoudl plan.

NOTE: A friend had a simular problem,  I don't yet know the solution, but they wanted nearly a thousand dollars to work on it and it's under warranty!!!!  (The cost was labor dropping it and re-installing it)  So call and ask or stop in and ask, you may wish to R&R it yourself.

Greg,

Two questions.

Does it have a safety low oil pressure shut down? If it does, the low oil pressure sensor may be bad. It is bypassed when the start switch is in the start position so the generator would run when the start switch is held on.

Has this generator sat for a long time without being run? Like more than a year. If so the stator may have lost it's charge and may need to be excited. If you think that may be the problem let me know and I can tell you how to do it.

Another two things to think about.  ???  ???

I have the same problem with my Onan. Please tell me how to excite the stator.
Thanks
Jobguy

Excuse me if this does not apply to your situation.

I've had a similar experience. Starts while cranking, then dies when on its own.
  My problem was that the fuel level was below 1/4 tank. Must be more than that as the fuel line intake is elevated inside the tank. This prevents you from draining the tank, leaving you high and dry in the campground.

Just an idea.

carson FL.

Simple answer  YES  many of the MHs shut off the Genset when gauge hits 1/4 tank of fuel.

jobguy said:

I have the same problem with my Onan. Please tell me how to excite the stator.
Thanks
Jobguy

Click to expand...

Jobguy,

First make sure you don't have low fuel as mentioned and rule out the oil pressure sensor. Use this as a last resort.

DISCLAIMER:

If you're not familiar with electricity please DO NOT try this!

I was shown how to do this and have done it once myself. I DON'T KNOW IF IT CAN BE DONE ON ONAN GENERATORS. IT IS DANGEROUS BECAUSE YOU HAVE A CORD WITH TWO MALE ENDS ON IT AND ONCE THE GENERATOR STARTS TO GENERATE ELECTRICITY THE MALE END IN YOUR HAND IS HOT. A generator repair shop showed me how to do this. The generator I had at the time was NOT an Onan. I do know that
THIS WILL NOT WORK ON AN INVERTER TYPE GENERATOR!!!!!
If anyone knows how to determine for sure if a generator needs it's stator excited, or if you know of a better way to excite the stator please jump in.


The way I was shown was to take a six foot extension cord, a porcelain socket, a 100 watt light bulb or fuse holder with 5 amp fuse and a male cord end.

About half way down the extension cord separate the wires. Cut the black wire and wire the porcelain socket or fuse holder in line. Cut the female end off the extension cord and put the male cord end on. Put the 100 watt light bulb in the porcelain socket or fuse in fuse holder.

With the generator running plug one end of the extension cord into one of the 110 volt outlets on the generator. Take the other end of the extension cord and AS QUICKLY AS POSSIABLE plug and unplug it into a hot 110 volt outlet. If you do it quickly enough the light bulb won't blow. The light bulb acts as a fuse.

Good Grief,
    I wouldn't do that under any circumstances on my ONAN.
I would go to the nearest ONAN shop/dealer, it'll be cheaper than buying a new one.

IMHO,  carson FL.

I had this problem on my old 1988 Coachmen Classic. It was a connection on a resistor that was burnt out on the circuit board. Just soldered a new piece of wire from the resistor to the circuit board and worked like new. 

Carson,

I wouldn't do that under any circumstances on my ONAN.

Click to expand...

Flashing a stator is a commonly accepted practice, and done correctly, will not damage anything. The caveat, as stated, is that it cannot and should not be done to an Inverter-type generator.

Where is the oil pressure sensor located? I have the same issue.

Are you sure your ohmmeter will accurately read resistances below 1 ohm?

Last January my genny (Onan 5500 Gold Marquis) started dying as soon as the start button was released. Turned out to be a direct short to ground in the transfer box. Finally got on the right track when I started it with the two breakers on the genny shut off and it kept running.

I would find Onan specific instructions for flashing if you really think you need to do this. I think you will find another problem.

Tom

This is a 12 year old message thread, I suspect they either have it fixed by now, or they have given up

Or electrocuted themself.

Didn?t even look at the dates...