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ImaginaryNumber's avatar
ImaginaryNumber
Explorer
Jun 17, 2013

Onan 4000 Microquiet KY no start - Oil level switch bypass

My 2004 Trail Lite 235s has an Onan Microquiet 4000 KY generator which has always started right up, but now won't start.

The rig has been parked for almost a year on a slight incline with the rear of the genset lower than the front. I have periodically exercised the genset, but a couple of months ago it would not start. My current project is to get it started and tuned up for our summer vacation.

Model: Onan 4000 Microquiet - 4KYFA26100K Spec K
S/N: D030493001

The genset cranks but fails to start. The fault code is 36.

Inspecting what I can see without removing the genset from the motorhome, looking through the throat of the air intake, the carb looks very clean, with no evidence of varnish. I verified fuel flow, drained the bowl, added SeaFoam liquid to the gas line, sprayed SeaFoam spray into the air intake, and changed and gapped the spark plug but it still won't start.

I was wondering if having the RV parked at an angle for an extended period might be activating the low oil switch. How can I identify the low oil switch wire from an accessible connector? The connector above the solenoid is the only one I see.

Also, the LED light on the remote control does not work.

Does anyone know how to access the low oil sensor wire from an accessible connector, or have any other ideas to get the genset started? It only has 10+ hours on it.

Or alternatively, any suggestions for service in the Boulder, CO area?

Thanks

13 Replies

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  • dan-nickie's avatar
    dan-nickie
    Explorer
    Jun 17, 2013
    I have a PDF manual I can email you if you want to PM your email to me.

    Edit: Beat me to it.

    But...my manual is different and I see there is a picture of the low oil switch on page 10-2 if you want it.

    I found this text that may help:
    Disconnect the low oil level shut down circuit.
    Locate the lead from the low oil level switch that
    comes out of the top the oil base below the
    spark plug. Separate the in-line quick connect
    where lead S2 J1-7 connects to the low oil level
    switch.
  • Kpackpackkelley's avatar
    Kpackpackkelley
    Explorer II
    Jun 17, 2013
    Ky service manual
    This may help. I would start by taking the gasoline solenoid off the carb at the bottom and clean it out. When you take it out there is a spring and pin in it . While you have it out apply 12 volts to it to make sure the pin pulls in that's what lets gasoline in the carb. I don't believe the spec k had a low oil pressure switch but check the parts manual on which spec had one. Good luck the others will be along shortly to help. Ps if you have a multimeter make sure you have 12.7 volts to your start solenoid and with start switch pushed you have 12.7 v coming out of start solenoid. No light on start switch sounds like low battery or bad connection at start solenoid.
  • Handbasket's avatar
    Handbasket
    Explorer
    Jun 17, 2013
    I dunno if you even have a low oil level switch (they're no longe used on 2800's, anyway), but if you've moved to a level spot,that should cure it; I think it's just a float on a swing arm. Have you tried cranking it with the chassis engine running? Sometimes that provides that little bit of extra voltage needed to crank one fast enough to start.

    Jim, "Don't get even. Get odd."

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