The truck turns over but will not fire, there is also no smoke coming out of the exhaust, I checked the fuses and #22 was blown so I did some research and then I pulled the fuel heater out of the fuel bowl and put it all back together and put a new fuse in #22 and it blew the new fuse. I read on another forum that you can test the pcm by unplugging it and putting a new fuse in and if it blows that one than it's not the pcm. I'm stumped, I have no idea what is going on with this truck and I've been working on it for 2 days and still can't figure anything out. I'm about ready to just give up on the truck, I've chased down wires and made sure all was good.

 

I read some where that the ground for the pcm is routed through the glow plug relay and that if the relay is bad that it could be poping the fuse like it's doing. Has anybody heard of that and can anybody help me out that knows what's going on with this truck

 

My service manual says that fuse #22 is for the fuel heater, 215 amp alternator voltage regulator, PCM power relay, and GP controller. Unhook the GP relay and see if the fuse still pops. If the fuse holds with the relay unhooked, the relay must be bad. I believe the 215 amp alternator is for ambulance duty, but you could unhook the large wire to the alternator and check it out if unhooking the GP relay doesn't work.
When you pulled the fuel heater, did you also pull the wire to the heater inside the fuel bowl? If not it could be shorting out.

 

Blowing fuse 22 is usually caused by a bad fuel bowl heater. unplug it on the outside of the filter housing (middle wiring connection) and you should be good to go. Most guys just eliminate the heater altogether and have no consequences, but if you'r worried about it gelling in the really cold stuff (I don't see your location) you can buy an updated heater from a lot of places.