Fuel pressure jumps to 60, then drops all the way to 0-5.
 

93 blazer 4.3 vortec. New fuel pump, new filter, new spider kit with regulator. Fuel pump relay doesnt seem to trigger every time, but when it does the pressure jumps to 60 for 2 seconds and then rapidly drops. I don't see any leaking around the spider or regulator, but it does seem to be coming out the ends of the poppets when I pulled one to look. Could the relay being defective cause pressure drop or is that a different issue entirely? Can't find any leaks.

The valves at the end of the injector shouldn't have fuel coming out of them while priming the pump. I would suspect that is where your fuel pressure is leaking down to.

Okay. It definitely is. Any idea what would cause that? Like I said, brand new unit.

From my understanding, the only thing that would cause that is a defective unit. What brand is it?

damn. Well I got it from O'reillies. They kept the box for the core so I can't say brand unless it's shown somewhere else? I just wasnt sure if there was any sort of signal the relay sends when it cuts off that told them to drain or something. It would really suck if this was a defective unit considering the hassle of getting it.

The fuel pump relay just feeds the pump itself, not the injectors.

It's recommended to use AC Delco units, they are the OEM brand, and known to be quality.

Yeah, I did see that a lot of people recommended that brand. I just happen to be in a bit of a time crunch and couldnt track that one down quick enough. This brand is the borg warner? So just to clarify, nothing else that you know of would create that problem except a bad unit? I can return it for a new one, but the problem I'm having is it seems to be the same issue I had before replacing it so I just wanted to be sure it wasn't anything else causing it.

Well, I put the new one in and the pressure is holding now. When the relay shuts off it drops from 58 to 53 about and then holds about there for a while. Unfortunately now it's only starting with the throttle pedal to the floor and then running rough and shuts off if I let go of the pedal. Was hoping it just needed to clear out air or something but it doesnt seem to be getting better. Still no trouble codes.