76 k100 won't shut off

Does it shut off if you turn the taps off at your fuel tanks..

 

Well, if the thumb screw is out it would have to be electrical. I am not Well versed on your wiring, but my second thought is a relay is sticking. If not that then a short between another hot lead.

Perhaps others can help more.

 

Cummins or detroit? By the looks of the avitar, cummins?
If cummins, I think there is a solenoid on the pump that gets hung up. The 5.9 in the 1st gen dodge pickups does the same same thing. You might also try a cummins forum and see what the pu guys have doen about it too. A pickup with an automatic trans is a sob to get shut down when the key wont work.

 

I'am not a Cummins expert but your fuel shut off solenoid is hung up open or you getting Constant power to it ..you should start by checking your power wire at the solenoid
I would of put in 4th grear orso with the brakes set and let the clutch out to kill it vs shuting the fuel supply off .. now you gota work harder to get it to fire again ..
Thats just me though

 

Next time it does that leave the key off and and see if it quits in a few seconds, 10-15 seconds…..

 

Quite a few posts deleted in this thread......or maybe it's just my phone.

 

Warn ignition barrel/key? Think an auto electrician would take long to nail it down.

 

The electrical wires break over time and the place they break is where the wires bend when you lift up the cab. Try running a new wire from the ignition switch to the engine to see if that is the problem. What engine? If it is a detroit, the shutoff kills the air or fuel, perhaps the mechanism needs adjustment.