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I jumpered the fuel pump on my buddy's 84 Fleetwood Brougham with 12v and the pump works great, (including new filter/inlet strainer)!!

I've located the fuse and relay--replaced both. Pump still won't run when ignition switch turned 'on'.

I guess I need a wiring diagram or a hint how to find a short in the 12 supply.
Any ideas?

(I just found out about this forum--and I think it's a great idea. Special thanks to David Smedley for his imput so far--he's helped me get this far with the car :)

Lee
 

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1968 Cadillac Sedan deVille, 1994 Chevrolet G20
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Not a problem. Anyway, Where did you jumper it? Try to find a connector that is taped up by the brake booster. This is the fuel pump prime connector. Give that a try. If it STILL doesn't prime, have someone listen to the relay to see if it clicks. If it doesn't, take a look at the oil pressure switch. The two parallel spades deal with the fuel system. Unfortunately, I completly forget what they are supposed to read. BUT, neither one of those terminals should be grounded when the harness is disconnected. The other terminal, the perpendicular one is the oil pressure light. That one should be grounded with no oil pressure.
 

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Thanks.

As a last ditched effort I thought I'd try bypassing the entire system and applied a jumper directly from the battery to the pigtail harness at the gas tank, grounding the other lead from the tank to the rear bumper to complete the circuit. It was nice to hear the pump work and see the fuel pressure gauge read around 10 psi (proper DFI level).

I'll continue with your troubleshooting ideas on the car tomorrow. I'm thinking I saw the oil pressure switch you mentioned. Is it a little metallic box (about the size of a cigarette pack) mounted near the floor on the passenger side with two sets of connectors attaching to it. (The box has a total of five pins or spades connectors). Two of the wires eventually lead to the fuel pump test terminal in the engine compartment, so I presume this is it.

My dad mentioned the slight possiblity that the pigtail has a bad connection within itself to create an open circuit, so I'll look into this possibility too.

Thanks again.

Lee Reichel
 

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1968 Cadillac Sedan deVille, 1994 Chevrolet G20
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Nope, but that box is important too. That tells the pump to prime. The switch is a little threaded shaft screwed into the engine in an oil passage.
 
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