Fuel Pump Harness Ground
03-05-2014, 05:45 AM
#1
Fuel Pump Harness Ground
Okie,
from what I was told, the owner was driving normally, suddenly the car just died, and he has to tow it back home cuz it refused to start.
I checked for him and found that the pump does not turn on.
after further investigation, it seems there is a problem with the wiring,
Fuel pump wiring that plugs into the Fuel Pump, there are 4 wires, all other 3 works EXCEPT the BLACK, AKA the GROUND wire, it's not "connected" for some reason, so the result is the pump will not turn on, if I jump the wire from the connector directly to the body, the car start and drives normally again.
so the question is, does anybody know where does the black ground wire ends up at ?? I checked the wiring diagram it seems that its ground to the body somewhere. I just dont know where right now. is it ground somewhere in the bottom of the car ?
Does anybody know ? it "seems" the black wire goes from the pump back to the front of the car ? I haven't been able to trace it down yet.
Thx
from what I was told, the owner was driving normally, suddenly the car just died, and he has to tow it back home cuz it refused to start.
I checked for him and found that the pump does not turn on.
after further investigation, it seems there is a problem with the wiring,
Fuel pump wiring that plugs into the Fuel Pump, there are 4 wires, all other 3 works EXCEPT the BLACK, AKA the GROUND wire, it's not "connected" for some reason, so the result is the pump will not turn on, if I jump the wire from the connector directly to the body, the car start and drives normally again.
so the question is, does anybody know where does the black ground wire ends up at ?? I checked the wiring diagram it seems that its ground to the body somewhere. I just dont know where right now. is it ground somewhere in the bottom of the car ?
Does anybody know ? it "seems" the black wire goes from the pump back to the front of the car ? I haven't been able to trace it down yet.
Thx
Last edited by nycgps; 03-05-2014 at 05:51 AM.
03-05-2014, 11:06 AM
#3
Be careful. Some stuff is turned on and off with the ground leg, not the power leg.
Turn the key off and see if the 12v goes away. If it does not, and grounding the pump turns it on, you cannot just ground the wire or the pump will run 24x7.
If you have the diagram open, look for it hitting some kind of switch before it hits ground. There might be a realy used. Relay could need seating, Fuse is usually on the power side, so if you have 12v, fuse is likely OK.
this is based on other cars, I have not done it with an 8.
Turn the key off and see if the 12v goes away. If it does not, and grounding the pump turns it on, you cannot just ground the wire or the pump will run 24x7.
If you have the diagram open, look for it hitting some kind of switch before it hits ground. There might be a realy used. Relay could need seating, Fuse is usually on the power side, so if you have 12v, fuse is likely OK.
this is based on other cars, I have not done it with an 8.
03-05-2014, 11:12 AM
#4
Be careful. Some stuff is turned on and off with the ground leg, not the power leg.
Turn the key off and see if the 12v goes away. If it does not, and grounding the pump turns it on, you cannot just ground the wire or the pump will run 24x7.
If you have the diagram open, look for it hitting some kind of switch before it hits ground. There might be a realy used. Relay could need seating, Fuse is usually on the power side, so if you have 12v, fuse is likely OK.
this is based on other cars, I have not done it with an 8.
Turn the key off and see if the 12v goes away. If it does not, and grounding the pump turns it on, you cannot just ground the wire or the pump will run 24x7.
If you have the diagram open, look for it hitting some kind of switch before it hits ground. There might be a realy used. Relay could need seating, Fuse is usually on the power side, so if you have 12v, fuse is likely OK.
this is based on other cars, I have not done it with an 8.
- key is on,
- tap another extra wire from the black fuel pump ground line to the body of the car.
other wise, the pump will not function at all.
the relay works because I checked it with the Check FP jumper wire, the relay clicks with key on, swap the relay next to it (cuz it's the same, CIRCUIT), same thing. so it's gotta be a grounding issue somewhere.
I have a feeling I missed something. just can't figure out what yet.
03-05-2014, 11:31 AM
#5
It is amazing what a rock under a car will do. Or a wire in a loom.
Do you know a network tech? If so, and he as a cable scanner, you can hook it up to the ground (some splicing and a connector required) and use the TDR function to tell you how far from the end the wire is broken.
I once had a nick in the insulation on the sense wire for 12 V at the fuel pump. Every time I went over a certain RR track, it bounced against a piece of flashing on the transmission casting and shorted out, blowing the fuse. Of course, it bounced back away as well, leaving everything fine. Changed the fuel pump, did not fix it. Upped the fuse, did not fix it. 4 hours into tracing every freaking wire in the car, found it. This was the SENSE line, not the power line, for the fuel pump. It had no use but to tell the ECU that there was 12V at the fuel pump.
I pulled the drawing I haver, looks like it is just a ground wire, just cannot tell where it grounds to.
Good luck...
Do you know a network tech? If so, and he as a cable scanner, you can hook it up to the ground (some splicing and a connector required) and use the TDR function to tell you how far from the end the wire is broken.
I once had a nick in the insulation on the sense wire for 12 V at the fuel pump. Every time I went over a certain RR track, it bounced against a piece of flashing on the transmission casting and shorted out, blowing the fuse. Of course, it bounced back away as well, leaving everything fine. Changed the fuel pump, did not fix it. Upped the fuse, did not fix it. 4 hours into tracing every freaking wire in the car, found it. This was the SENSE line, not the power line, for the fuel pump. It had no use but to tell the ECU that there was 12V at the fuel pump.
I pulled the drawing I haver, looks like it is just a ground wire, just cannot tell where it grounds to.
Good luck...
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