# 1994 Pathfinder fuel pump Electrical



## dwcald (Mar 26, 2017)

I have a 1994 Nissan pathfinder that cranks but doesn't start unless I jump the fuel pump to the battery(how I got it Home). I have checked power and have power to the relay on three connections, I can switch the relay with the main and it works fine, I have replaced the relay, the one circuit without power is the wire towards the fuel pump, I tried jumping that to no avail still no voltage at the pump, I know I must be missing something but have no clue where else to look. Any help would be appreciated


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## smj999smj (Jan 1, 2006)

If you are jumping the fuel pump relay to send power to the pump and there is no power at the pump, you have an open circuit on that wire between the relay and the pump that will need to be traced and repaired.


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## dwcald (Mar 26, 2017)

I have disconnected the security control module under the drivers seat, no change It will only run while fuel pump is jumped to the battery , is there a relay or something that controls the fuel pump from the security system?
The wires from the fuel pump relay under the hood are of a smaller size then the actual wire at the pump. Trying to figure out where else to check.


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## smj999smj (Jan 1, 2006)

According to the wiring diagram, there are two, BLACK/WHITE wires at the fuel pump relay harness connector which are powered by a single, 10A fuse. So, if you unplug the fuel pump relay, you should confirm power at those two wires with a 12v test light with the key in "ON" or "START" positions. The fuel pump relay harness connector has two more wires: WHITE/BLUE and RED/BLUE. The RED/BLUE wire is part of the ground circuit for the fuel pump relay's solenoid (which is inside of the relay). When the relay is energized, it causes the switch side of the relay to close and send power to the fuel pump and the IACV air regulator. The RED/BLUE wire goes from the fuel pump relay harness connector to ECM pin #104 ; it is the ECM that provides the ground to this circuit. So, with the ECM and fuel pump relay disconnected, you should have no continuity between chassis ground and the RED/BLUE wire (if it does, then it is shorted). You should also have good continuity through the RED/BLUE wire with no excessive resistance when testing from the relay harness connector to the #104 pin of the ECM harness connector. Also, ECM harness connector pin #115 , a BLACK wire, should have good continuity to ground as it is the ground for the ECM. 
The WHITE/BLUE wire at the fuel pump harness connector starts as a single wire then splices (probably the reason why the wire is smaller at the pump connector), one to the IACV air regulator, which powers the air regulator and goes to ground. The other side of the splice goes to the fuel pump, where it powers the pump and goes to ground. If you jump a BLACK/WHITE wire to the WHITE/BLUE wire and the key is "on," you should have power to the fuel pump. If you don't, you have an open circuit in the WHITE/BLUE wire and it needs to be traced and repaired (I would also check for power at the IACV air regulator if there is no power at the pump because it may help out in the diagnosis of the open and tracing it). 
If you do have power to the pump when you jumped the relay, remove the jump wire and install a known good relay. If that doesn't fix it, it would be likely that the driver is bad inside the ECM and the ECM needs to be replaced. 

| Repair Guides | Wiring Diagrams | Wiring Diagrams | AutoZone.com


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## dwcald (Mar 26, 2017)

Keep trying to trace this out and while doing so I discovered a 6 wire connector disconnected under the steering column, There are white, orange and red/whitestripe wires This connector (both male and female ends) is wire tied to the column, could this be effecting the fuel pump and worth plugging back in?


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