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Pulled Fuel Pump Relay and Car Kept Running?

I was planning on changing the fuel filter in my 95 Grand Prix GTP (3.4L). As per recommended instructions, I wanted to bleed the fuel lines by shutting off the fuel pump and running the car to depressurize the lines. So I pulled the fuel pump relay, started the car, but it just kept running. I assumed it would run for maybe 10 seconds or so, but I ran it for 10 minutes and it kept on going. Before anyone asks, I did pull the right relay according to the label on the cover and the user manual. Has this happened to anyone else before? Is there any reason the fuel pressure switch would keep the pump running even though the relay is pulled?

I just find it rather strange and I'd love for someone to explain to me why this would happen.

Thanks in advance.

-407

Reply to
Aaron407
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It happens because there is an oil pressure activated switch in parallel with the relay.

Reply to
aarcuda69062

Someone has made some changes to the fuel pump wiring, or jumpered across the relay. Time to get out the ohmmeter and start tracking down where they did it.

--scott

Reply to
Scott Dorsey

You pulled the wrong relay!

Reply to
dahpater

You don't need to pull the relay. Even if you pull the relay, and try to start the vehicle, (which "shouldn't start"), you will still have pressure in the lines.

Reply to
dahpater

I don't know your particular car but on some cars the fuel pump gets power from the fuel pump relay and has a redundant supply that is activated by the oil pressure switch. Try pulling the wire off the oil pressure switch too and see if it dies.

Steve B.

Reply to
Steve B.

Ok, I'll try that out, thanks for the advice.

-407

Reply to
Aaron407

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