1999 Cadillac STS Fuel pump

DOUGLAMA

MEMBER
1999 CADILLAC STS
V8
FWD
AUTOMATIC
120,000 MILES

No power to fuel pump, fuse and relay are good. On fuse block at relay, term 87 12v all the time. Term 85 12v for about 2 sec. On the fuel pump 2 elec plugs, 3 wire and 4 wire, which plug is for pump and which wire is the hot wire. Can the fuel pump be hotwired

Sunday, May 24th, 2009 AT 8:34 AM

2 Replies

FACTORYJACK

MECHANIC
4,159 POSTS

The four wire is pump and sending unit, the three wire is pressure sensor. Gray wire pin B is hot from relay, and black pin C is ground.

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Sunday, May 24th, 2009 AT 11:53 AM

DOUGLAMA

MEMBER
2 POSTS

It was a bad fuel pump.
I disconnected the plug from the pump then used a paperclip to jumper term 87 & 85, this applied power to the plug long enough for me to test for power and a quick plug in, to test the pump.
After removing the pump I checked continuity, open circuit, I also saw why the fuel guage didn"t work, the fingers that ride on the resistor, were worn off
I checked the dealer price 545.00, the best deal on the internet 250.00.
I located a used unit out of an Olds Aurora (98-99) for 75.00.

Thanks again

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Sunday, May 31st, 2009 AT 5:53 AM