1999 Cadillac STS Fuel pump

1999 CADILLAC STS
120,000 MILES • V8 • FWD • AUTOMATIC
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DOUGLAMA
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  • 2 POSTS
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
May 24, 2009 at 8:34 AM
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FACTORYJACK
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  • 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.
May 24, 2009 at 11:53 AM
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DOUGLAMA
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  • 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
May 31, 2009 at 5:53 AM
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