I have an '03 h. o. with the FASS fuel system installed on it, been this way for about 6 months now,I put an electric fuel pressure gauge on it about 3-4 months back, the needle has always had a slight movement in it form time to time but not always, recently about 2 1/2 months ago I put a PMCR on the truck after a few weeks I started getting a small stumble, only under very light acceleration and not always there kinda like a miss, here lately it has gotten more evident. I thought it might be due to the PMCR, but Mark at TST said they have only seen one at speeds down the interstate not down low like mine. My gauge quit the other day and then started working again now it has quit altogether, so Iinvestigated it, checked all the circuits ground, switched 12+, everything checked ok, so I listened for the fuel pump to come on and run it didnt, no 12v hot---dead, also have a code set p0628 fuel pump relay circuit low, or fuel lift pump control circuit low, What do you check for this code?? Brad at FASS fuel systems said ground his pump to - bat and run switched 12v+ to the fuse box with a 15 amp fuse inline anyone tried this with a FASS fuel system?? Doesn't the computer till it when to start and stop pumping? Where is the old fuel pump relay, is it the one on the back of the cp-3? should I replace this relay? I think maybe now my stumble was this fuel pump not working and the injector pump working on the suction method which the FASS system is designed to do in case of lift pump failure.
Help anyone with ideas????????

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