No power to fuel pump
Thread Starter
Heel & Toe
Joined: Aug 2004
Posts: 16
Likes: 0
No power to fuel pump
Hi I have an 89 c4 convertible.
Would just stop while I was driving. I bought a new fuel pump and installed but could not get car to turn over.
I ran power to the G line and heard a relay click by the firewall but the Pump would not come on.
I have looked at my fuse panel and there is no FP slot for a fuse, I am assuming there is only a relay???
What should I look for next I am thinking of replacing the in tank harness and have allready switched the relay with others that are the same.
Car almost turns over with starter fluid to air intake but with the pump not runing is just starving for fuel.
Is there any thing else that could factor in on turning the pump on and off???
Thanks for any possible solutions
Would just stop while I was driving. I bought a new fuel pump and installed but could not get car to turn over.
I ran power to the G line and heard a relay click by the firewall but the Pump would not come on.
I have looked at my fuse panel and there is no FP slot for a fuse, I am assuming there is only a relay???
What should I look for next I am thinking of replacing the in tank harness and have allready switched the relay with others that are the same.
Car almost turns over with starter fluid to air intake but with the pump not runing is just starving for fuel.
Is there any thing else that could factor in on turning the pump on and off???
Thanks for any possible solutions
Le Mans Master
Joined: May 1999
Posts: 6,519
Likes: 1,305
From: Windermere FL
Couple things to check. I believe the 89 has a oil pressure sensor that shuts off the fuel relay if the oil pressure drops. There is a bypass that allows it to pressurize during start. Have someone turn on the ignition (but not start the car) while you listen to see if you can hear the fuel pump prime for a few seconds then shutoff.
Sounds like you need to get a Field Service Manual and go thru the diagnastics before you start replacing anymore parts.
Sounds like you need to get a Field Service Manual and go thru the diagnastics before you start replacing anymore parts.
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
There should be a FP fuse in/on the panel take another look....should be in the middle toward the bottom of the panel.
The oil pressure sensor is part of the pump circuit.
The fuel pump relay is located on the firewall between the brake booster and the distributor.
Without oil pressure - the fuel pump will only run for 2 seconds (max) if you turn the key to the "run" position but don't start the engine...this function is a safety feature.
If your having a fuel starvation issue and a new pump it might be best to check the fuel pressure at the rail (using a fuel pressure gauge) to determine if you have any pressure/proper pressure.
Note: the '89 has problematic fuel injectors (Multech) which are non ethenol compliant. If you have good/proper fuel pressure, spark at the plugs then you may have a fuel delivery problem....ie problematic fuel injectors.
The oil pressure sensor is part of the pump circuit.The fuel pump relay is located on the firewall between the brake booster and the distributor.
Without oil pressure - the fuel pump will only run for 2 seconds (max) if you turn the key to the "run" position but don't start the engine...this function is a safety feature.
If your having a fuel starvation issue and a new pump it might be best to check the fuel pressure at the rail (using a fuel pressure gauge) to determine if you have any pressure/proper pressure.
Note: the '89 has problematic fuel injectors (Multech) which are non ethenol compliant. If you have good/proper fuel pressure, spark at the plugs then you may have a fuel delivery problem....ie problematic fuel injectors.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
The ECM closes the fuel pump relay for 2 seconds when you switch the ign to run or crank and it will turn on the fuel pump if it gets reference pulses from the distributor. The fuel pump relay will also be turned on if the oil pressure switch sees 4 psi or more oil pressure.
