when i turn my key on my fuel pump runs continusly doesnot stop and the truck will not start if i shut the key off and back on the fuel pump runs fro about 4 or 5 seconds and the truck runs great i changed relays and a fuel pressure regulater anyone have an ideal wtf is wrong with this truck thanks

 

I have been a similiar problem with my '99 4.2. If i crank the engine it won't start. But if I turn the key to the on position I hear a buzzing sound for a couple of seconds then it stops. The engine then fires. Have you solved your problem? What was it?

 

I suspect you both have ground faults for the PCM. Check them all carefully. Otherwise, the PCM is most likely bad.