Chevy & GMC Vans

I changed the pressure reg and supply and return lines am throwing a 54 code low voltage to fuel pump. changed fuel pump relay no change disconected it after norm operating temp no change. when it sits for 15 min it takes a while to start when the oil pressure reaches 15psi it fires. turn ignition on dont hear pump turn on when i shut it off i hear the pump. wanna know if i should just change the fuel pump or what thanks

I have a question I am looking in a haynes manual i have a 95 astro and the scematics for the wiring are the 93 and earlier models the 95 should have a red wire to prime the fuel pump mine has the gray wire and has the 4 prong relay and the 95 should have a five prong. If i hook a jumper wire to the prime wire my van starts right up no problem and it shows no codes until i shut it off again and then it shows low voltage to the pump. should i put a new ecm in it or re wire it to make it prime when i turn on ignition.

Just a guess,but how about a bad oil pressure switch not allowing the pump to prime?.

I replaced that too and when i take relay out it stays running right now i have a toggle hooked up to the prime wire i turn toggle on start with no problem and then turn toggle off has no issues when i do that so its running on oil pressure switch im thinking its got to be a short from ecm to relay or ecm

You may have a burned through wire. The pump should prime with the key selected for on. The ECM is in the right front kick panel correct? Follow the wire bundle from that through the firewall where it crosses over the right engine valve cover. You need to remove the doghouse to do this. If that loom is sitting on the valve cover, it probably has some burnt insulation and wires. Check it out. If all this is ok and both ECM fuses are good, you may need an ECM.

Ok I will check it out and post findings