Onan stop solenoid

I have a solenoid on a 40 year old mdjf 15kw that has voltage when starting generator however in the run position it loses voltage so it shuts off the fuel causing generator to quit. Remove the solenoid and it runs great but have to push down on fuel shutoff lever to kill generator. We test the oil pressure sensor and the high temp sensor to see if they are causing the solenoid to shut down and both are functioning properly. We have troubleshooted this thing to death. I have several original manuals and parts catalogs but none have a wiring diagram. Does anyone have any suggestions what could be causing this problem.Btw, the stop solenoid is new. It does actuat up when starting but immediately goes down when I release the start switch. Thanks for any help!

How many wires on it?

Theres many with 2 circuits. 1 is a larger pull and the second more of a hold.

There's only one wire connected to the solenoid.

If the same as my Onan. Then fuel is held on by relay in control box which requires voltage from ac side of generator. I believed it also goes through a trip switch located at generator control panal. I may have a drawing which I can email later today.

A drawing would be helpful. There is a red wire going to one of the related terminals in the control panel that's not providing any voltage. Not sure if it's supposed to or not. Thanks!

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Originally Posted by jnuttall

A drawing would be helpful. There is a red wire going to one of the related terminals in the control panel that's not providing any voltage. Not sure if it's supposed to or not. Thanks!

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PM me your email address and I will send you the PDF files latter today.
On my generator the fuel shut off is energized when cranking. Motor starts, but will only keep running if control board senses AC power from generator coil, and no fault conditions are present.
By the way mine is and MDL4 20Kw

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Originally Posted by jnuttall

There's only one wire connected to the solenoid.

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My 50 year old MDJB (long gone now) solenoid had two coils. Coil with heavy wire to pull in the solenoid, and a coil with very fine wire to hold it in. Only one wire goes to the solenoid. When the plunger pulls in it closes an internal contact that keeps the "run" coil energized. If you remove the end cap from the solenoid you may see the the fine wire connecting the Rub coil broken, or the internal switch contacts burned. This same symptom happened to the MDJB in 1987. I was able to solder the broken wire back onto its terminal.