Fuel Pump Problem
Thread Starter
Melting Slicks
Joined: Sep 2001
Posts: 3,494
Likes: 36
From: Livermore Ca
St. Jude Donor '05-'06
Fuel Pump Problem
I get no fuel pressure from my 89.
I went around a conner and when dead.
I've tested and replaced:
Oil Sending unit, Fuel Pressure Relay and Fuel Pump
Check out the fusable link near the battery tested good.
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).
Questions that I have.
Is there another fusable link for the fuel pump? If so where is it?
I have not changed out the module under the cap.
And if there is a broken connection how is the fuel pump wiring routed?
Thanks...
I went around a conner and when dead.
I've tested and replaced:
Oil Sending unit, Fuel Pressure Relay and Fuel Pump
Check out the fusable link near the battery tested good.
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).
Questions that I have.
Is there another fusable link for the fuel pump? If so where is it?
I have not changed out the module under the cap.
And if there is a broken connection how is the fuel pump wiring routed?
Thanks...
- 1986 Original Owner -
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From: North Yorkshire, England
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Originally Posted by Coupe89
I get no fuel pressure from my 89.
I went around a conner and when dead.
I've tested and replaced:
Oil Sending unit, Fuel Pressure Relay and Fuel Pump
Check out the fusable link near the battery tested good.
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).
Questions that I have.
Is there another fusable link for the fuel pump? If so where is it?
I have not changed out the module under the cap.
And if there is a broken connection how is the fuel pump wiring routed?
Thanks...
I went around a conner and when dead.
I've tested and replaced:
Oil Sending unit, Fuel Pressure Relay and Fuel Pump
Check out the fusable link near the battery tested good.
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).
Questions that I have.
Is there another fusable link for the fuel pump? If so where is it?
I have not changed out the module under the cap.
And if there is a broken connection how is the fuel pump wiring routed?
Thanks...
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
Correct, this is the first thing I thought..fuse 10a. Check it and if good, energize terminal G and check for 12v at the connector at the tank. If no 12v go to the fuse and use a test light to see if there is current there. Disconnect terminal G and take the fuel pressure relay off and use a short jumper wire and insert it into the first terminal and the last terminal of the fuel pump relay connector. Turn the key "on" and if the new relay is bad this will send the 12v to the fuse. You know the pump is working and just not recieving 12v through the circuit. Let us know what you find.
Last edited by RRT vette; Oct 11, 2006 at 08:39 AM.
Team Owner
Joined: Jan 2003
Posts: 20,254
Likes: 221
From: Summerland B.C. Canada
Originally Posted by Ray Quayle
You didn't mention the Fuel Pump Fuse. It's in the Fuse Panel on the passenger side dash.
Power from relay and oil pressure switch goes to fuse panel and then pump.
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
58 psi????? sounds awefully high to me! Only 1 fusible link runs both the oil pressure switch (backup for the fuel pump relay) and the fuel pump relay. Sounds like you have an open somewhere between the fuse box and the pump.
Looked at your profile MODS alot, so that may explain the high pressure...curious, what size injectors are you running?
Looked at your profile MODS alot, so that may explain the high pressure...curious, what size injectors are you running?
Last edited by rick lambert; Oct 11, 2006 at 11:04 AM.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 32
From: The Top of Utah
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.
It is amazing to me that all these parts failed at one time. And STILL the problem exists.
RACE ON!!!
Originally Posted by Coupe89
I've tested and replaced:
Oil Sending unit, Fuel Pressure Relay and Fuel Pump
Oil Sending unit, Fuel Pressure Relay and Fuel Pump
RACE ON!!!
Thread Starter
Melting Slicks
Joined: Sep 2001
Posts: 3,494
Likes: 36
From: Livermore Ca
St. Jude Donor '05-'06
Originally Posted by rick lambert
58 psi????? sounds awefully high to me! Only 1 fusible link runs both the oil pressure switch (backup for the fuel pump relay) and the fuel pump relay. Sounds like you have an open somewhere between the fuse box and the pump.
Looked at your profile MODS alot, so that may explain the high pressure...curious, what size injectors are you running?
Looked at your profile MODS alot, so that may explain the high pressure...curious, what size injectors are you running?
That what I'm guessing...
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Thread Starter
Melting Slicks
Joined: Sep 2001
Posts: 3,494
Likes: 36
From: Livermore Ca
St. Jude Donor '05-'06
Originally Posted by CFI-EFI
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.It is amazing to me that all these parts failed at one time. And STILL the problem exists.
RACE ON!!!
RACE ON!!!
BTY just checked the fuse box with the test light. All power.
So from the fuse box does the wire route its self to the pump or does it go thought the ECM? Dont have the book with me right now
Thread Starter
Melting Slicks
Joined: Sep 2001
Posts: 3,494
Likes: 36
From: Livermore Ca
St. Jude Donor '05-'06
Originally Posted by rick lambert
try a temporary wire from the fuse to the fuel pump...should confirm it.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
From the fuse panel the wire goes to the pump. Did you test for 12v at the pump connector with terminal G energized? If the fuse is good and it shows it, and there is no voltage at the pump connector...then there is a problem between the fuse and the connector. Looks for insulations shrinking and or bare wires. Also test the ground on the connector. The other wire is for the guage.
(On my 86) The pink wire (ckt 30) goes from the fuel pump assembly to the dash guage. Tan/white wire (ckt 120) is the 12v to the fuel pump. Black wire (ckt 150) is the ground to the fuel assembly/pump.
(On my 86) The pink wire (ckt 30) goes from the fuel pump assembly to the dash guage. Tan/white wire (ckt 120) is the 12v to the fuel pump. Black wire (ckt 150) is the ground to the fuel assembly/pump.
Thread Starter
Melting Slicks
Joined: Sep 2001
Posts: 3,494
Likes: 36
From: Livermore Ca
St. Jude Donor '05-'06
Originally Posted by RRT vette
From the fuse panel the wire goes to the pump. Did you test for 12v at the pump connector with terminal G energized? If the fuse is good and it shows it, and there is no voltage at the pump connector...then there is a problem between the fuse and the connector. Looks for insulations shrinking and or bare wires. Also test the ground on the connector. The other wire is for the guage.
(On my 86) The pink wire (ckt 30) goes from the fuel pump assembly to the dash guage. Tan/white wire (ckt 120) is the 12v to the fuel pump. Black wire (ckt 150) is the ground to the fuel assembly/pump.
(On my 86) The pink wire (ckt 30) goes from the fuel pump assembly to the dash guage. Tan/white wire (ckt 120) is the 12v to the fuel pump. Black wire (ckt 150) is the ground to the fuel assembly/pump.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
Originally Posted by Coupe89
The pump does not go on when a 12v is applied to terminal G. I'll rase the car and look under it....
EDIT: Wiggle the connector/wires while testing with the voltmeter
Last edited by RRT vette; Oct 11, 2006 at 01:58 PM.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 32
From: The Top of Utah
Originally Posted by Coupe89
All these parts did not fail. I tested and replaced them with new ones that I tested also. Need to get some sort of baseline.
Originally Posted by Coupe89
Dont have the book with me right now
RACE ON!!!
Thread Starter
Melting Slicks
Joined: Sep 2001
Posts: 3,494
Likes: 36
From: Livermore Ca
St. Jude Donor '05-'06
Originally Posted by CFI-EFI
So why did you waste your time testing parts you were going to replace anyhow? A baseline consists of checking components and replacing the bad parts. You are going to have a lot of money tied up in what would have been a very inexpensive repair.
Originally Posted by CFI-EFI
No matter. You haven't used it yet. Why start now?
RACE ON!!!
RACE ON!!!
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
Lets see if this is right.
When you directly apply 12v from the battery to the fuel pump connector tan/white the pump will run and supply fuel pressure?
With a hot wire from the positive side of the battery to terminal G of the ALDL and the fuel pump connector is connected the fuel pump does not run?
You have 12v at the fuse panel on the fuel pump fuse (10a) or it lights up with a test light? You should touch both sides of the fuse to make sure the connection in the back of the fuse panel is good and both sides should light up.
Still having terminal G going, you go to the rear of the car and take the fuel pump connector loose. Use a voltmeter on the fuel pump connector that goes back toward the front. You should have 12v there and it sounds like you don't, which means there must be an open in the circuit 120 or a bad ground.
AGENT 86 did this for you: http://members.shaw.ca/corvette86/Code%2054.pdf
You didn't mention a code showing up, but following this would help.
When you directly apply 12v from the battery to the fuel pump connector tan/white the pump will run and supply fuel pressure?
With a hot wire from the positive side of the battery to terminal G of the ALDL and the fuel pump connector is connected the fuel pump does not run?
You have 12v at the fuse panel on the fuel pump fuse (10a) or it lights up with a test light? You should touch both sides of the fuse to make sure the connection in the back of the fuse panel is good and both sides should light up.
Still having terminal G going, you go to the rear of the car and take the fuel pump connector loose. Use a voltmeter on the fuel pump connector that goes back toward the front. You should have 12v there and it sounds like you don't, which means there must be an open in the circuit 120 or a bad ground.
AGENT 86 did this for you: http://members.shaw.ca/corvette86/Code%2054.pdf
You didn't mention a code showing up, but following this would help.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 32
From: The Top of Utah
Originally Posted by Coupe89
True. But I'll have spair parts for later on.
Originally Posted by Coupe89
I've used it. It doesn't tell me to look behind the fuse box. Nor how the car is wired.
Originally Posted by RRT vette
When you directly apply 12v from the battery to the fuel pump connector tan/white the pump will run and supply fuel pressure?
With a hot wire from the positive side of the battery to terminal G of the ALDL and the fuel pump connector is connected the fuel pump does not run?
You should have 12v there and it sounds like you don't, which means there must be an open in the circuit 120 or a bad ground.
With a hot wire from the positive side of the battery to terminal G of the ALDL and the fuel pump connector is connected the fuel pump does not run?
You should have 12v there and it sounds like you don't, which means there must be an open in the circuit 120 or a bad ground.
RACE ON!!!