Fuel Pump Problem

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Oct 12, 2006 | 11:45 AM

#21

RRT vette

Le Mans Master

Joined: Feb 2006

Posts: 8,753

Likes: 9

From: Louisiana

Quote:

Originally Posted by CFI-EFI

simply running 12 volts to the pump wouldn't make it run either.

RACE ON!!!

Correct, it would also need a ground.

Oct 12, 2006 | 12:22 PM

#22

Coupe89

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Melting Slicks

Joined: Sep 2001

Posts: 3,494

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From: Livermore Ca

St. Jude Donor '05-'06

Your telling me that if the pump runs with out a ground. Then it a bad ground?
At the same time should I get 12v (Tan/Wht) from the wiring harnest. Because I don't.

Last edited by Coupe89; Oct 12, 2006 at 12:26 PM.

Oct 12, 2006 | 12:35 PM

#23

RRT vette

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Joined: Feb 2006

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From: Louisiana

Quote:

Originally Posted by Coupe89

Your telling me that if the pump runs with out a ground. Then it a bad ground?
At the same time should I get 12v (Tan/Wht) from the wiring harnest. Because I don't.

The pump needs 12v and a ground to run. I don't know you have a bad ground but it would take some troubleshooting to find out.

YES, you should have 12v (Tan/Wht) from the wiring harness. If the fuse is good and lights up then there is a problem between the fuse panel and the connector from the harness.

EDIT: how exactly did you make the pump run? Was it out of the tank?

Oct 12, 2006 | 01:22 PM

#24

Coupe89

Thread Starter

Melting Slicks

Joined: Sep 2001

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From: Livermore Ca

St. Jude Donor '05-'06

I applyed 12 volts from the battery to the pump connector where the Tan/Wht would go. The pump turned on. I'll look at the wiring...

CFI-EFI is confusing me

Last edited by Coupe89; Oct 12, 2006 at 01:28 PM.

Oct 12, 2006 | 01:40 PM

#25

rick lambert

Le Mans Master

Joined: Oct 2003

Posts: 6,130

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From: seattle WA

I know it's silly, but did you have the key on when you checked the voltage at the pump?
When you ran the wire directly from battery to pump was the pump still attached to the harness?

Oct 12, 2006 | 02:11 PM

#26

kalister1

Drifting

Joined: Sep 2005

Posts: 1,867

Likes: 3

From: Pasadena Maryland

Quote:

Originally Posted by Coupe89

CFI-EFI is confusing me

He is trying to tell you to keep your wallet closed and in your pocket until you have completed all the troubleshooting steps and isolated the problem. It sounds like it might be as simple as a broken wire under your car. When the key is on you found 12 volts at the fuse box but no voltage at the fuel pump connector. When you ran a wire from the battery to the fuel pump it spins up. So you have a good pump, a good fuse, it sounds like a wire problem.

Oct 12, 2006 | 02:48 PM

#27

CFI-EFI

Race Director

Joined: Sep 2000

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From: The Top of Utah

Quote:

Originally Posted by rick lambert

I know it's silly, but did you have the key on when you checked the voltage at the pump?

With the key "On" and engine "Off", there will only be power at the fuel pump for the first 2 seconds of key "On". ASSUMING there are no other problems.

Quote:

Originally Posted by Coupe89 Opening Post

I also tested the Terminal G of the ALDL +12 volts and the pump does not turn on.

If a direct +12v to the tan/wht on the fuel pump connector I get normal pressure(58 psi).

Quote:

Originally Posted by CFI-EFI Post #7

If the pump doesn't run with terminal "G" energized and it does run when you energize the connector at the tank, then it is pretty obvious that there is problem is between the two. The fuse IS between the two, but you say it checks out.

Doesn't that pretty well sun up the problem? Or have I missed something? I can think of another possible problem, but THIS is a problem, regardless.

Quote:

Originally Posted by Coupe89

CFI-EFI is confusing me

I haven't said anything contradictory or that should be confusing. If you have your head wrapped around some misconceptions, reading my posts could cause confusion. You are making this way more expensive and difficult than it has to be. Have you read, studied, and understood the fuel pump operation as described in your FSM?

RACE ON!!!

Oct 12, 2006 | 03:13 PM

#28

Coupe89

Thread Starter

Melting Slicks

Joined: Sep 2001

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From: Livermore Ca

St. Jude Donor '05-'06

Does the wiring from the front of the bottom or in the car to the the pump?

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Oct 12, 2006 | 07:13 PM

#29

CFI-EFI

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From: The Top of Utah

Quote:

Originally Posted by Coupe89

Does the wiring from the front of the bottom or in the car to the the pump?

You don't get down off an elephant, you get down off a goose.

FSM

RACE ON!!!

Oct 12, 2006 | 07:54 PM

#30

Fasterer

Instructor

Joined: May 2005

Posts: 132

Likes: 0

From: Torrington CT

Cfi-Efi is right on. The power goes from the fuse to the pump. if you put 12 volts to the pump at the tank connector and it pumps its not the pump. If you put 12 volts to terminal "g" of the diag connector the pump should also pump. if not its the wiring to the pump or the fuse. there's no magical way to fix the wiring you have to follow it back from the front or forward from the back till you find the problem. I would try another fuse first just for giggles. If you have a nother person with you you can ground a test light and plug it in the power feed wire in the fuel pump plug at the tank . This will allow you to watch and see if it lights while the other person cranks the car for the 2 or 3 seconds the relay will try to energize the pump. For what its worth.

Oct 12, 2006 | 10:22 PM

#31

RRT vette

Le Mans Master

Joined: Feb 2006

Posts: 8,753

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From: Louisiana

If you just turn the key "on" the fuel pump circuitry will only energize for 2 seconds commanded by the ECM. With terminal G energized the fuel pump circuitry will be energized until the wire is removed from terminal G. I have never traced the wires from the fuse panel to the pump so here is a guess. On my 86 the harness wires disappear on the right side of the tank. I assume it enters the wall of the interior behind the carpet and along the inside door jam to the fuel panel. This is just a guess and someone else might know exactly, that has had to trace these wires.

Energize terminal G and use the voltmeter on the tan/white wire on the harness at the tank. The connector must be disconnected and you are testing the female part that go back to the front and not male part that goes into the tank.

Behind the fuel panel (tan/white wire) goes into the panel and comes back out and has the fuse to protect it. Test both terminal on the fuse and both should light up with a test light. I have typed most of this about 4-5 times and don't know how to explain it better. Use good judgement or have someone that know how to test wires, help you.

Oct 13, 2006 | 12:22 AM

#32

Coupe89

Thread Starter

Melting Slicks

Joined: Sep 2001

Posts: 3,494

Likes: 36

From: Livermore Ca

St. Jude Donor '05-'06

Quote:

Originally Posted by CFI-EFI

You don't get down off an elephant, you get down off a goose.

I dont get it....

Reread #7 I'll get to it later on tonight

Last edited by Coupe89; Oct 13, 2006 at 12:26 AM.

Oct 13, 2006 | 12:01 PM

#33

CFI-EFI

Race Director

Joined: Sep 2000

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From: The Top of Utah

Quote:

Originally Posted by CFI-EFI

You don't get down off an elephant, you get down off a goose.

Quote:

Originally Posted by Coupe89

I dont get it....

That is the perfect response to:

Quote:

Originally Posted by Coupe89

Does the wiring from the front of the bottom or in the car to the the pump?

Quote:

Originally Posted by Coupe89

Reread #7

I have read, and reread, #7. I wrote it. I fully understand it. Do you? Why do you want me to reread it?

Quote:

Originally Posted by Coupe89

I dont get it....

That could be your credo.

RACE ON!!!

Oct 13, 2006 | 12:39 PM

#34

Ray Quayle

- 1986 Original Owner -

Joined: Apr 1999

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From: North Yorkshire, England

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CFI-EFI, The guy is having a bad enough time, you didn't have to say it twice (Post #33 and #34).

Oct 13, 2006 | 01:50 PM

#35

CFI-EFI

Race Director

Joined: Sep 2000

Posts: 17,298

Likes: 33

From: The Top of Utah

Quote:

Originally Posted by Ray Quayle

CFI-EFI, The guy is having a bad enough time, you didn't have to say it twice (Post #33 and #34).

I didn't mean to double post. I'll take care of that. Since comprehension seems to be a problem, a double post might not be such a bad idea. I will delete post #34. Your post, quoted above ,will become the new #34.

RACE ON!!!

Last edited by CFI-EFI; Oct 13, 2006 at 01:52 PM.

Oct 14, 2006 | 09:58 AM

#36

RRT vette

Le Mans Master

Joined: Feb 2006

Posts: 8,753

Likes: 9

From: Louisiana

Quote:

Originally Posted by Coupe89

I dont get it....

You got this thing figured out yet?

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