i had this issue also. turned out to be a bad oil pressure sensor (i hooked it up incorrectly and fried the contacts shut) which caused the pump to run continuously. the way it works is you have the pressure switch in parallel with your fuel pump relay. when you turn the key to on/start, the pcm will kick the relay on for 2 seconds to build the needed fuel pressure at the rails. The engine fires and now oil pressure has been created and obviously stays until engine get shut down. this pressure closes the contacts in your oil pressure switch which alows voltage to power your fuel pump continuously until pressure is dropped. This is why you can still hear your pump running in the tank for several seconds after you kill the motor. takes a bit for the oil pressure to bleed down and open the contacts in the oil pressure sensor. I believe its also a safety precaution in case of severe accident like a roll over.... do you want your fuel pump stil running after you roll over and are unconcious just cuz your key is still in the ON position? i sure dont!!!
anyway, i know all this cuz i was having a similar issue and had to dig through all the wiring diagrams. makes complete sense to me now and i opted to keep it wired that way. some guys delete it but i personally like the extra safety. so it sounds like you have it wired incorrectly AND/OR your sensor is shot like mine was. i think it was like 10 bucks at autozone. cheap thing to replace.
BTW, im sure youve figured it out by now but ill say it anyway. The sensor doubles as a oil pressure sensor AND fuel pump switch. thats why there are 3 wires on it.
TAN - goes to oil pressure gauge on your cluster
ORANGE - +12v going to one side of contacts on switch
GRAY- comes off of other side of contacts of switch and goes to fuel pump
PHEW!! hope that helps
P.S. i drove around for a week having to get out and unplug the fuel pump everytime i parked somewhere before i figured this out....
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Originally Posted by genIIIdude
