M939A2 Engine Won't Shut Down When Turned Off

[Conical One]

I have a 1986 M939A2 that has been running great. Batteries died due to lack of use. After recharging batteries, I started the truck up and it ran great. Left if running for 4 hours to charge batteries fully. When I shut it down the engine stopped as expected. I decided to restart it to check batteries and it cranked right up. Then I tried to shut it down again AND . . . it won't shut down. I can go as far as pulling the key out of the ignition. I had to use the emergency shutoff to get it to shut down. Now I take the key out (previous owner put key ignition in) and the kill the battery switch and power lights are still on the transmission switch and ABS lights even though all other gauges go to zero. I suspect there could be voltage still flowing and this is causing my batteries to die out even with everything shut down. I have replaced the ignition switch and the same thing happens. I am thinking something in the Protective Control Box may have fried.

__________

After further digging, it appears that the Fuel Shutoff Solenoid (particular to M939 series vehicles) is most likely the culprit. Will examine in more detail and order a new one. I will post results for others to learn from.

 

[fpchief]

It's the solenoid most likely. I left mine off. If you buy one, make sure it is the 24v one. The 12vdc solenoid looks pretty much the same. I have zero problems pulling out the shutoff cable and save the $60 or whatever the shutoff cost.

 

[WillWagner]

You can remove the FSOV and run a fully mechanical shut off with a cable.

 

[Conical One]

You can remove the FSOV and run a fully mechanical shut off with a cable.

I like to keep it fully operational and have ordered the Cummins solenoid from my neighbor company that works on Cummins generators. Got his discount and paid $28.75 for full Cummins OEM part. Thanks for the input.

 

[fpchief]

I like to keep it fully operational and have ordered the Cummins solenoid from my neighbor company that works on Cummins generators. Got his discount and paid $28.75 for full Cummins OEM part. Thanks for the input.

Good price no doubt.