No keyed voltage to fuel pump relay

[Donniejr81]

Ok I have a problem here goes. I swapped out the dash and engine harness, ECM, instument panel...pretty much everything on my 85. I turn the key and the fuel pump relay will not close. I pulled the relay and the circuit sending juice to the fuel pump is ok 12.7v...just no voltage signal to close the relay. I double checked the voltage and fuses at the fuse block under the dash and everything was good there. I believe my problem is somewhere between the ignition switch and fuel pump relay. My tach and boost lights work and the car will crank. Is there something between the fuse block and relay I should double check? Please help because Im out of ideas.

 

[rag231]

electrical problem

Did you change out the relay itself? I ve seen where a little water gets inside and begins to rust the parts inside. Also if that voltage was with the car "off" it seemed a volt low. (I know I need all the voltage to my pump that I can get)

 

[Donniejr81]

I went ahead and tried a different relay just to make sure and no change. This has me totally stumped the voltage is at the fuse block and everywhere else just gets lost somewhere on its way to the relay. Could it possibly be the ECM or a bad PROM chip? Are there any fusible links, I couldnt find any in that circuit. Thanks.

 

[rag231]

problems

ok , so you say the car will crank. Have you tried to bypass the relay ( with a jumper wire) to make sure the pump was still working. Then the car can RUN, and not just CRANK. If you have voltage to and after the relay the only thing left is the pump. I think also on the fuel pump assy ( at the top of the tank) there is a connector to check for power as well. Has pump been changed? I have heard of people changing gas tanks and not realize that they had the naturally aspirated ( vacuum) pump assy on it and forgot to connect the connector or when they did they didnt realize that it had only the ground and fuel tank level wire. Hope this helps.

 

[Donniejr81]

I didnt think of that Ill give it a try. I appreciate the help. Thanks- Donnie

 

[BlackBandit]

i've never seen the schematic for an 85 but I would assume it would be ground controlled. In other words you would have voltage to the relay and the ecu would connect the ground to enable current to flow. You said there is no power to the relay. Does that mean that using a multimeter with one probe connected to a metal ground you don't have valtage at any of the pins on the relay connector? If this is the case you probably have a blown fuse or bad wire somewhere. Also, on 87's (i know yours is an 85) the fp relay coil power comes from the a fuse other thab the fp fuse so make sure you check all of your fuses not just the fp one.