Onan 4kw won't stay running after start button released

Discussion in 'Class A / Diesel Pushers' started by Carcruiser, Mar 20, 2007.

  1. Carcruiser

    Carcruiser New Member

    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
     
  2. JEEPGUY

    JEEPGUY New Member

    RE: Onan 4kw won't stay running after start button released

    Greg, I know what your talking about. In 99 I had the same problem to a 2.8 genset but I knew little about the gen so I took it in to a service center. This is what they said,
    Rotor assem. is shorted, voltage reg. is bad.
    Rotor cost...375.00
    voltage reg...140.00
    to R&R genset and replace rotor &reg...536.00

    So looking at a $1000.00 repair on a a $1500.00 genset, I just bought a new one and installed it myself. I've kept the old one thinking I'd fix and use it somewere. (still setting in the Garage.)

    Only thing Icould tell you is they tested resisance through rotor, it was 12.4 KOHMS
    Good luck.
     
  3. Guest

    Guest Guest

    RE: Onan 4kw won't stay running after start button released

    check the points.. that old of a genset had points,,,
    They are located in a small square box on the almost back of the genset ,,,
    there should be a tech sticker on the set to let u know what the setting is for the points and spark plug gap... if not check u'r owners book on the set (If u have one) If not let me know by pm (i work for cummins/onan/thermoking, and i can look it up for u)
    Also ,, has this genset been sitting for awhile????
     
  4. Carcruiser

    Carcruiser New Member

    Re: Onan 4kw won't stay running after start button released

    Hello, I did check the points and they are good. I took the stator to Cummins Bridgeway here in Cleveland. They had a calibrated meter and the tech there said the T1 and T2, T3 and T4 windings were okay. But the Q1 and Q2 measured .6 ohms, well below the expected 3.47 ohms. He brought out another stator and showed me that it did read around 3.35 ohms. He said that the stator is bad and needs replaced. I connected 2 12VDC car batteries in series thru and inline 5 amp fuse to the brush wiring. I did this with the voltage regulator removed. The output voltage was 62VAC. Then I revved the engine up, and the output went to 105VAC. So, I am assuming that if I would have put 3 or 4 12VDC car batteries in series, the output definitely would have went up without having to rev the engine. I connected a drill up to the A.C. output and it ran it fine, granted the voltage was low.
    730, just wondering if you think that the stator is my problem. If so, do you have any connections on getting a stator for my generator?
    Thanks!
    Greg
     
  5. Guest

    Guest Guest

    Re: Onan 4kw won't stay running after start button released

    It sounds like the exciter field is burnt up in u'r stator..
    If u can give me the model # and build date (Include month)..
    And serial # i can see what i can do...
    We don't have alot of the old gas parts around anymore,,, but i'll check...
    (since all the new Diesel sets are on the maket,, that is usally what we have parts for,,)
     
  6. Carcruiser

    Carcruiser New Member

    Re: Onan 4kw won't stay running after start button released

    I have a Onan 4BGEFA26101F 4KW Emerald I generator . From what I can make out, the serial number looks like KB_0282665. I can't make out the letter or number where the underscore is. As for the build date, I could not locate anything to indicate the date. The manual I have says the part number is 220-4135-04. I took a closeup picture of the tag and can email it and a few other pictures to you if that would help.
    Thanks
     

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