it still seems like a short somewhere to me...maybe in the pdc itself(if thats possible) my only suggestion is to hardwire the pump to the engine run position from the ignition switch...either that, or replace the PDC and its whole harness, or trace every inch of the wiring(inside the PDC and out) to find the short...the relay should be rather hard to blow(with all the fuel issues I have ever had...and I have had a lot, I have yet to blow a relayc) check all your engine grounds as well, just on the off chance, shorts are the worst, I know, but you have to keep plugging away at it till you find out whats wrong(or get sick of it and bypass it)