Truck won't shut off.

Dump the clutch

 

You should have read my response before this, this response was for someone else not you.

Your fuel pump is not shutting down. Even if you take off the terminals for the battery, your vehicle is running on the alternator once it starts.

This means your fuel pump or the solenoid or switch or what ever that is controlling it has failed. It’s giving the go head signal but its not giving the all stop signal.

If its a mechanical fuel pump, then the fuel line has a cut off switch somewhere That’s not cutting the fuel off.

Either way you need to go on a hunting trip.

 

I'm sorry, what's comical, is it's not the space shuttle ( that alone dates me). A diesel has to have a fuel shutoff. We can be a rude bunch, but to a seasoned driver, this stuff just seems funny to us. I'd have felt like a fool telling the boss the truck won't shut off, but that was back in a time, where you could do your own problem solving, and got an "atta boy" from the boss for doing so. That wiring diagram would have me screaming into the night. Zap, oh, oh, now the heater goes on with the right turn signal, and such.

 

Each truck is different and this being 20 year old unit some custom work might have been done on it, making it largely impossible to diagnose over the net,


First step would be pull the fuse panel, look at diagram find the fuse or relay for the fuel pump, pull it and see if that shuts it down.

If yes then replace and see if it works now,

If it doesn’t shut down after new relay then move on to next leg of the diagnostics chain, that is to the fuel pump, see if it’s internal or external of external see if it has a solenoid on it, have it tested and apply voltage to it to see if it shuts down. Not sure how it’s done but this is next step, if fuel pump is found to be working then a relay mid stream is the culprit.

 

When no one knows and you don’t have a mechanic in your pocket (one who specializes in your make and model) it’s best to make a list of possibilities and just start going down em.
It’s a ##### but when I’m doubt hit it with the parts cannon.
If you are electricity inclined you could start testing resistance/voltage and track down your issue.