Onan generator will not stay running

[svaron]

I have an Onan 20MDL4B. When I start the generator, after 10 seconds the reset button pops out and the generator shuts down until I reset the pin. the engine has not run long enough to overheat And the mechanical oil gauge shows good pressure. Any thoughts???

 

[mtadamek]

Probably a bad oil pressure sender. Could be a short in the board. Check all your sender connections, at the sender, and the board.

 

[yachtsmanbill]

Check the points on the front of the motor just above the oil filter. I believe these are oil pressure "close to run" and are often overlooked... ws

 

[Canuck Dennis]

Are you talking about the red reset on the front or the smaller ones about the size of a pencil point ? each one has a different function

 

[Boatnut]

Does anyone have the wiring diagramj of the subject generator? If so can you post a copy or send me a copy, I doubt you have a difficult problem, but it saves a lot of time getting to the answer using a diagram.

 

[svaron]

Yes, it is the small pencil thin reset pin. I will check the connections although I don't believe that is the problem as they are screwed on to the connection tab. At the 'T' fitting attached to the block there are what seems to be 2 oil sensor units. Why are there 2?

 

[svaron]

Well, after my last post, I decided to take another look at my connections And it turned out that the 2 wire attached to the governor were slightly loose... Tightened them up and all is well....

Thank you for everyone's input !!!!

 

[svaron]

I spoke too soon....I ran the genset for a half hour with a load on and it ran fine.... No reset issues. When I restarted it an hour later the same thing happened, the reset tripped. I think it might be a faulty reset button. I will call Sam's on Tuesday to order one... Hopefully they have one.

 

[Canuck Dennis]

Check first to see what that sensor does, you may have 2 problems not one, one of the resets is I believe to protect against vr damage. Check the manual wiring diags before assuming one issue only.

 

[captbuddy]

Similiar thing happened to my Onan. Turned out to be a loose (broken leg) on a diode on my electronic board.
captbuddy

 

[svaron]

Very strange. I left the genset alone for 9 hours, went to start and now it is running fine with a full load on it.

 

[REBrueckner]

Sounds like an intermittent problem, something loose, a poor connection; almost always a pain to diagnose. The "loose wires" may not have been an issue, it's often difficult to tell...

A simple course of action is to continue checking for loose connections and broken and damaged wires. Loose wires which move with vibration can fray strands causing an intermittent connection.

Check CAREFULLY for a loose in line fuse providing power to your control box. Bill Allen had a similar 1980's ONAN problem this past fall on our trip from NJ to Fla...I bypassed every sensor, checked relays, wires, connections, etc, etc...all seemed fine.....but did not know there was such a fuse...I don't think my 1970's 12KW ONAN had such a fuse....I don't know if your newer 20 KW has such a fuse.....A pro subsequently advised BIll that a weak fuse holder spring when warm/hot allows a poor fuse connection!!!! That was it!!!!!

 

[svaron]

Good suggestion. I will keep looking and let you know

Thank you for everyone's input!!!