Not getting signal to fuel pump

MARKED0210

MEMBER
1997 OLDSMOBILE BRAVADA
180 MILES

My fuel pump recently stopped pumping, but I tested it and it works, the relay works because I manually tested it but there is no signal to it. I have already dropped the tank and battery tested the pump, checked every fuse, and changed the relay.

Monday, September 5th, 2011 AT 3:16 PM

7 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Check the fuel pressure with a gauge if its within specs if okay-check the injector/s if its pulsing on a TBI-Spider type-remove upper plenum and look for fuel on the poppet valves. Could also be the computer controlled of the fuel pump relay circuit

SPONSORED LINKS

Was this

answer

helpful?

Yes

Monday, September 5th, 2011 AT 3:38 PM

JDL

MECHANIC
16,098 POSTS

How did you test the pump? A no load test isn't worth much. I've seen faulty pumps that would run fine on the work bench, but wouldn't make any pressure. Did you check for good voltage and ground at the pump motor?

Was this

answer

helpful?

Yes

-1

Monday, September 5th, 2011 AT 3:39 PM

JDL

MECHANIC
16,098 POSTS

There is a redundant power supply to the fuel pump from oil pressure switch. If the switch is functiuonal and has voltage, the pump will run, regardless of relay.

Was this

answer

helpful?

Yes

Monday, September 5th, 2011 AT 3:50 PM

RASMATAZ

MECHANIC
75,992 POSTS

JDL-Affrimative on the fuel pump and oil pressure sending unit it powers the pump when the engine fires up-the relay is only good for the 2secs effect

Was this

answer

helpful?

Yes

Monday, September 5th, 2011 AT 4:09 PM

MARKED0210

MEMBER
2 POSTS

Thank you all for your great advice guys, but I had a spare PCM in the garage and I switched it out and lo and behold everything came back to life! Unfortunately now the PCM has to be brought to the dealer to be flashed or reprogrammed as it runs terrible. If you have any advice on that subject my ears are wide open!