Electrical fuel pump issue, URGENT - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

allenms240 · 07-14-2012, 12:05 AM

Hello all,
Last night I was working on my car, fixing a fuel leak I had. When I put my sending unit back on, I believe the power line was crushed between the unit and the tank. I went to start my car, and the fuel pump wouldn't work. I shorted out the circuit.
The EGI relays have been replaced, so has the blown fuel pump fuse. I have bench tested the actual pump and the pigtail from the sending unit and they are working properly.
I tested continuity from pin 104 (fuel pump relay wire) to the relay pin and confirmed the wire wasn't broken between those two spots. I also tested between the relay to the fuse, which showed continuity. I have also tried to bypass the relay to no avail.

Now I noticed that when my pigtail for the fuel pump isn't plugged in, my car and dash lights turn on correctly without lag. When I plug it in and turn the key to ON position from ACC, everything in the car shuts off for about 3-5 seconds, and then comes on.
I'm not quite sure what to diagnose now. Could it be the ECU, how would I test that? What else is there I can test?

ka4life87 · 07-14-2012, 01:46 PM

U getting power at the relay?

allenms240 · 07-14-2012, 02:16 PM

To test this, would I just test for 12v at the relay socket with ecu plugged in and key in the ON position?

allenms240 · 07-14-2012, 04:47 PM

So I tested at the relay, I am getting power there. I noticed that the EGI relay clicks, but the EGI pump relay does nothing with the key in the ON position.

Also, I tested for power at the pig tail. I got about 7v in the two middle slots, and 0v from the other 3.

Any ideas?

jholman · 07-14-2012, 06:37 PM

Dumb question. You have power at the pump or no?

silvildo72 · 07-14-2012, 06:47 PM

Just hardwire it aka kill switch and cut off the purple and black wire going to the pin 104, Here's the write up for it : How TO: 240sx Hardwire Fuel Pump : 240SX Technical Forum I had the same probleme and worked great for me.

jholman · 07-14-2012, 06:52 PM

^^^that may be the easiest way. And works just fine

allenms240 · 07-15-2012, 08:22 AM

I am not getting power at the 12v wire in the back. I am, however, getting 12v at the fuse. So between the fuse and thE pigtail in thE back is my problem. I am currently chasing down that wire from the back through the cabin and see what I get.
If I cannot figure this out by tonight, I will have to hardware it for transportation purposes.

allenms240 · 07-16-2012, 12:31 PM

Fixed.
There was an electrical short in the sending unit of the fuel pump

07-14-2012, 12:05 AM	#1
allenms240 Zilvia Member Join Date: Nov 2011 Location: Arizona Age: 30 Posts: 201 Trader Rating: (16) Feedback Score: 16 reviews	Electrical fuel pump issue, URGENT Hello all, Last night I was working on my car, fixing a fuel leak I had. When I put my sending unit back on, I believe the power line was crushed between the unit and the tank. I went to start my car, and the fuel pump wouldn't work. I shorted out the circuit. The EGI relays have been replaced, so has the blown fuel pump fuse. I have bench tested the actual pump and the pigtail from the sending unit and they are working properly. I tested continuity from pin 104 (fuel pump relay wire) to the relay pin and confirmed the wire wasn't broken between those two spots. I also tested between the relay to the fuse, which showed continuity. I have also tried to bypass the relay to no avail. Now I noticed that when my pigtail for the fuel pump isn't plugged in, my car and dash lights turn on correctly without lag. When I plug it in and turn the key to ON position from ACC, everything in the car shuts off for about 3-5 seconds, and then comes on. I'm not quite sure what to diagnose now. Could it be the ECU, how would I test that? What else is there I can test?

07-14-2012, 06:37 PM	#5
jholman Leaky Injector Join Date: Sep 2010 Location: Va bitches Age: 32 Posts: 145 Trader Rating: (0) Feedback Score: 0 reviews	Dumb question. You have power at the pump or no? __________________

07-14-2012, 06:52 PM	#7
jholman Leaky Injector Join Date: Sep 2010 Location: Va bitches Age: 32 Posts: 145 Trader Rating: (0) Feedback Score: 0 reviews	^^^that may be the easiest way. And works just fine __________________

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07-14-2012, 01:46 PM	#2
ka4life87 Leaky Injector Join Date: Jun 2012 Location: casa grande Posts: 104 Trader Rating: (0) Feedback Score: 0 reviews	U getting power at the relay?

07-14-2012, 02:16 PM	#3
allenms240 Zilvia Member Join Date: Nov 2011 Location: Arizona Age: 30 Posts: 201 Trader Rating: (16) Feedback Score: 16 reviews	To test this, would I just test for 12v at the relay socket with ecu plugged in and key in the ON position?

07-14-2012, 04:47 PM	#4
allenms240 Zilvia Member Join Date: Nov 2011 Location: Arizona Age: 30 Posts: 201 Trader Rating: (16) Feedback Score: 16 reviews	So I tested at the relay, I am getting power there. I noticed that the EGI relay clicks, but the EGI pump relay does nothing with the key in the ON position. Also, I tested for power at the pig tail. I got about 7v in the two middle slots, and 0v from the other 3. Any ideas?

07-14-2012, 06:47 PM	#6
silvildo72 Leaky Injector Join Date: Aug 2010 Location: Ottawa Age: 29 Posts: 67 Trader Rating: (4) Feedback Score: 4 reviews	Just hardwire it aka kill switch and cut off the purple and black wire going to the pin 104, Here's the write up for it : How TO: 240sx Hardwire Fuel Pump : 240SX Technical Forum I had the same probleme and worked great for me.

07-15-2012, 08:22 AM	#8
allenms240 Zilvia Member Join Date: Nov 2011 Location: Arizona Age: 30 Posts: 201 Trader Rating: (16) Feedback Score: 16 reviews	I am not getting power at the 12v wire in the back. I am, however, getting 12v at the fuse. So between the fuse and thE pigtail in thE back is my problem. I am currently chasing down that wire from the back through the cabin and see what I get. If I cannot figure this out by tonight, I will have to hardware it for transportation purposes.

07-16-2012, 12:31 PM	#9
allenms240 Zilvia Member Join Date: Nov 2011 Location: Arizona Age: 30 Posts: 201 Trader Rating: (16) Feedback Score: 16 reviews	Fixed. There was an electrical short in the sending unit of the fuel pump