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sunshinelock's avatar
sunshinelock
Explorer
Jul 14, 2016

Video: Onan 3600 LP Generator Hunting Surging 300 to 400 Hz

My generator is propane. It was running my air conditioner fine yesterday then shut down. It's been surging since. I did a bit of research and see that it could be the governor. I was going to see how far off of 60Hz I was at, but see I'm about 300 to 400 Hz. Seems a bit excessive.

Any tips on what I can do to fix this?

Video link below.

https://youtu.be/m0dBwZxuQDg
  • My Onan Microquiet does not produce a a very pretty sine wave, and I could imagine a multimeter being fooled by multiple voltage peaks in a single cycle. Or as already hinted at, a bad voltage regulator could be mangling the waveform even more than usual. Listening to the video, the engine speed sounds close to correct as far as my ear can tell. Definitely a job for an oscilloscope.
  • Triker33 wrote:
    Voltage regulator


    Voltage regulator does not affect the frequency, only the voltage regulation.

    With that said, the way the OP checked the frequency is suspect.. There is now way in the word that a non inverter generator can output 300hz to 400hz unless it was designed that way from the beginning.

    OP has either a two pole (3600 RPM) or four pole (1800 RPM) gen head, commonly with most gens they are two pole 3600 gen heads direct coupled to the engine..

    Now, I would suspect the OP may have misread the meter and it was actually 30.0 HZ-40.0 HZ but that would mean the engine is running way to slow BUT the voltage is way to high for that low of frequency...

    I suspect there is nothing wrong with the GENERATOR HEAD, but the problem resides on the ENGINE side. Engine is STARVING for fuel when it is "hunting" (reving up and down) or ignition problems..

    Since it is LP that would rule out carb problems but there IS a "demand" regulator and other associated LP gas safety items that would be suspect and could cause the engine to hunt.
  • Tom_M wrote:
    Something is wrong with your meter. At 300hz the generator would be turning over 15,000 rpm and would self destruct in short order. The AC voltage rises when the RPM increases so 126 VAC indicates that the generator is probably only running slightly over 60hz.


    x2- that thing would be screaming.
  • Triker33 wrote:
    New regulator will fix it. If it doesn't stay at 60HZ don't run it.


    Voltage regulator or fuel regulator?
  • Something is wrong with your meter. At 300hz the generator would be turning over 15,000 rpm and would self destruct in short order. The AC voltage rises when the RPM increases so 126 VAC indicates that the generator is probably only running slightly over 60hz.
  • New regulator will fix it. If it doesn't stay at 60HZ don't run it.

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