95 gmc jimmy fuel pump won't shut off/fuel pump relay - Hot Rod Forum : Hotrodders Bulletin Board
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Old 08-14-2005, 07:59 PM
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95 gmc jimmy fuel pump won't shut off/fuel pump relay

I'm pulling my hair out with my 95 gmc jimmy 4.3L 4wd. Yesterday the fuel pump started running and wouldn't shut off. Got up this morning and the battery was dead (of course). Replaced the fuel pump today and the new fuel pump won't shut off either. Got a new fuel pump relay switch, but can't find the location of the switch. I'm not even sure that is the problem. Any help would really be appreciated.

Thanks in advance,

Gary

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Old 08-14-2005, 08:05 PM
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Gary...I know it's under the hood, usually on the firewall near the center.

I am moving this to the electrical forum....you should get a definite answer therte.
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Old 08-15-2005, 03:53 PM
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relay

Doc here,

You got me on that one too...Do you have a courtesy Center either under the Dash or in the engine bay, where the relays are located? You may want to look there first.

The owner's manual may give a clue as to where that may be located also.

Things to try..Find the fuse marked Fuel Pump, pull it and hope it fuses the control Circuit (Relay coil) And listen For the "Click" and track it from there.

Another is have someone pull the ground cable as you "audio Explore" For the "Click" and pull the relays going on and off until the pump shuts down. That'll be the offender..

Sounds like you have a source voltage on the coil at all times you need to remove to the "HOT IN RUN ONLY" side of the switch..or some welded relay contacts..

Did you recently install something electrical?

Doc
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Old 08-16-2005, 05:24 AM
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Thank you for your reply. Recently installed oil pressure sender---car ran fine for a day---then fuel pump started running continuously. I found 2 relay's in the glove box behind a panel, but not sure if these are the correct relay's to replace. They look identical to the new relays that I bought...but again...not sure. I wonder if the oil pressure sender is the right one for the car.

Any ideas,

Gary
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Old 08-16-2005, 06:49 AM
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The fuel pump relay is located in the relay center, the relay center is located behind the instrument panel compartment box. Let me know if you need more info.

Steve
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Old 08-16-2005, 03:58 PM
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Oil sender

Doc here,

It may be possible that Oil sender is the wrong one , of failed rapidly after you installed it , but not enough to make note on the gauge.

If I remember right that system has an oil pressure over ride to the relay to shut down the pump under zero oil pressure conditions..In addition it has prime wire to over ride it while cold starting..perhaps the internal resistance of that sender has changed and it thinks it's out of oil or cold starting..

Go here:
http://www.autozone.com/servlet/UiBr...3d8020539a.jsp

Get a schematic for it for free, (your going to have to change the vehicle, It's set for Corvette) and follow the circuit down..see if that's not how its wired..the problem may just lay in the sender value.

Doc
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Old 10-28-2010, 05:49 AM
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Plz tell me you found out the answer caz the same thing is happening to mine
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Old 10-28-2010, 07:10 AM
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Quote:
Originally Posted by garystrosnider
I'm pulling my hair out with my 95 gmc jimmy 4.3L 4wd. Yesterday the fuel pump started running and wouldn't shut off. Got up this morning and the battery was dead (of course). Replaced the fuel pump today and the new fuel pump won't shut off either. Got a new fuel pump relay switch, but can't find the location of the switch. I'm not even sure that is the problem. Any help would really be appreciated.

Thanks in advance,

Gary
It will most likely be the oil pressure sending unit / switch (combination) went bad

The pump relay primes the system( via 2 second pulse from ecm ) and then the oil pressure closes the leaf switch inside the op sender once vehicle starts and makes oil pressure.It allways has power and if the switch hangs closed it will run forever. The oil sender is a sender/switch comb that also moves the oil pressure gauge. Either part is subject to failure. Sounds like the pump side went bad.
The fastest way to tell would be to listen for the pump then unplug the switch and see if The pump quits. the switch will be located behind the distributor.Should have 3 wires to it.

Last edited by latech; 10-28-2010 at 07:17 AM.
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