mack1

If it is your truck and you are going to keep it, I would reccommend that you list it on AllData and get some good prints for it. I have prints on 4 and 6 cylinder vehicles of that year and it shows that the ECM B fuse does not power the PCM at all. The only input from that fuse to the PCM is a signal telling it that the oil pressure if up, thus the PCM knows to pulse the fuel injectors.

I would suspect that you have shorted the wire to the pump motor when you changed it out. A good test would be to unplug the connector at the tank, then locate the pump relay and feel or listen to it as a friend switches the ignition from off to on (not start). If the PCM is working, it should pull in that relay for about 2 seconds, then release it. One click for each off/on sequence at the ignition switch.

In any event, I would do more checking before buying a new PCM. Like you said, they don't like to take them back, even at wrecking yards.

Very best regards,
Mack1