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 KS/N: D030493001The 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

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."

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.

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 thatcomes out of the top the oil base below thespark plug. Separate the in-line quick connectwhere lead S2 J1-7 connects to the low oil levelswitch.

Thank you for the suggestions Handbasket, Kpackpackkelley, and dan-nickie.I tried starting the genset with the engine running and it cranked fine but did not start.I looked through the service manual but could not identify exactly where the connector pinout for the low oil switch is. I'll have more time to look tomorrow.Thank you for the service manual references.

The spec K does not have a low oil level switch. If the carb is OK, check the spark plug and/or coil.JimL

Onan 4000 Microquiet KY no start - Oil level switch bypass

13 Replies

Bobbo
Explorer II
Jul 05, 2013
If you exercise monthly, you really shouldn't need the stabilizer. The gas gets flushed before it has time to evaporate.
ImaginaryNumber
Explorer
Jul 05, 2013
Thanks to everyone who responded with suggestions and resources. For closure and post-op follow-up, I concluded that the carb jets were probably irreparably fouled with varnish and made an appointment at Best RV in Denver, an authorized Onan repair center, for professional diagnosis and repair. The cost was $500+ for new carb and installation. They did not remove the genset from the RV.

I am thinking about installing a see-through in-line fuel filter right before the carb so that when I put the RV in storage, I can measure some Sta-Bil or SeaFoam into the fuel line, run the genset a little, and watch the stabilizer flow into the carb.

Does that, and exercizing the genset monthly, sound like a good idea?

Thanks.
ImaginaryNumber
Explorer
Jun 20, 2013
Snowman9000 wrote:
Maybe call this guy?

Thanks, Snowman9000. I did give him a call.
Snowman9000
Explorer
Jun 19, 2013
Maybe call this guy?
Kpackpackkelley
Explorer II
Jun 19, 2013
That is a pretty good trick. You could take a wrench and grind the outside edges very thin so you can get on that bottom nut. But first try the screw on the bottom to empty the bowl and then hit the prime switch to run gas out of that outlet and see if it might clean it out. And when your turning it over to start it tap lightly on thay gas soleniod and see if it helps.
Its called the float bowl drain valve in the op manual you may have a little water in the bottom of the carb so try to drain it.
ImaginaryNumber
Explorer
Jun 19, 2013
Well, I verified spark and fuel flow, and even got it to run for a a short time but it appears to starve out a few seconds after the start switch is released. KpackKelly mentioned

"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..."

How can I get the solenoid off with the carb on the genset and the genset in the Trail Lite compartment? I can't seem to get a wrench on the fuel solenoid because the carb bowl drain is in the way.

Thank you.
dan-nickie
Explorer
Jun 18, 2013
Sent.....good luck.
Kpackpackkelley
Explorer II
Jun 18, 2013
dan-nickie wrote:
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.

Hey Dan could you send me a copy of your manual. Packkelley@gmail.com
Generator_Jim
Explorer
Jun 18, 2013
The spec K does not have a low oil level switch. If the carb is OK, check the spark plug and/or coil.

JimL
ImaginaryNumber
Explorer
Jun 18, 2013
Thank you for the suggestions Handbasket, Kpackpackkelley, and dan-nickie.

I tried starting the genset with the engine running and it cranked fine but did not start.

I looked through the service manual but could not identify exactly where the connector pinout for the low oil switch is. I'll have more time to look tomorrow.

Thank you for the service manual references.