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Chrenan
Joined: 15 Jan 2003
Posts: 3903
Location: Canada
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 Posted: Fri Jun 17, 2005 3:12 am Post subject: Interesting Observations on Fuel Pumps and Relay Replacement |
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Ok, so I replaced both fuel pumps and the fuel pump relay. Here are some interesting things I've noticed since then:
1. When I turn the key to the start position, the fuel pumps now run for a a few seconds to pressurize the fuel system. With the old pumps and relay, this would happen sometimes, but not always, which would force me to pressurize the system manually using the "cross-wiring" solution - jiggling the side view mirror adjust knob to run the fuel pumps. Seems funny since the relay I replaced was manufactured in 2001, the new one was manufactured in 2004. I can't imagine the "old" one from 2001 had gone bad already, and I'm assuming this is related to the relay replacement and not the pumps.
2. When I used to jumper slots 30 and 87 on the relay board to run the fuel pumps, the wire I was using as a jumper would get really hot to the touch. When I did the same thing with the new pumps installed, the wire wasn't hot at all. Is this a result of the new pumps drawing less amps?
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1987 951 - M193 Version for Japan |
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Ozzie
Joined: 12 Mar 2005
Posts: 4448
Location: Townsville, Qld. Australia
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| Posted: Fri Jun 17, 2005 7:38 am Post subject: |
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I'd say one of the pumps was knackered.
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance |
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numbbers
Joined: 05 Nov 2002
Posts: 1910
Location: Highlands Ranch, Colorado
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| Posted: Fri Jun 17, 2005 10:26 am Post subject: |
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Well, you have answered both your questions by your assumption for number 2. Yes, one or both of your old fuel pumps was/were drawing too much current. That caused the jumper wire too get hot, and also caused the old relay to burn out, as all that current was flowing through the contacts of the relay. So, it sounds like you have cured the problem.
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1980 924 Turbo |
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Paul
Joined: 02 Nov 2002
Posts: 9491
Location: Southeast Wisconsin
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| Posted: Fri Jun 17, 2005 11:27 am Post subject: |
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| Which may have been a dirty ground at the pumps.... |
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Chrenan
Joined: 15 Jan 2003
Posts: 3903
Location: Canada
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| Posted: Sat Jun 18, 2005 12:04 am Post subject: |
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Interesting.
All in all, while the car was still running before, the new pumps definitely give me added peace of mind...
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1987 951 - M193 Version for Japan |
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