91 240sx won't start

[hmart95367]

I checked for spark that's ok, My problem is electrical this has happen before and some how it fixed itself. It cranks fine but there's no fuel presurre. I have replaced... fuel pump, sending unit, fuel pump relay and fuse (s). Here is the problem. I get 12v at the electrical connector, I don't hear the pumping like usual. I pull it out of the tank, lay it on the it's side and I'm still not getting any power to the pump. I turn the key on the pump works for about 5 seconds and it stops. I have power to the sending unit, when I pull the pump apart from the unit and connect 12v directly to the pump it works great. Put it back together and inside the tank and no juice to the pump. Somehow during crank it looses 12v to the pump??? Someone help, my kid is driving my 8 cylinder 4x4 using alot of gas!!

[vancouverbc]

The pump is only supposed to be on for 5 seconds. The computer is not going to keep pump on if car has not started. if the fuel pump comes on, then there is fuel pressure so car should start. im no genius though.http://img522.imageshack.us/my...5.jpg
Modified by vancouverbc at 12:24 AM 2/13/2008

[hmart95367]

Thanks for the in-put Vancouverbc, I found the problem in a fusible link under the fuse box in the engine compartment. There are three thick white wires under the box. These are wires that come from the pos side of the battery they are fused together and go to the alt. These wires some how touched together and when heat, current and all that electricity is on it cut the power to the fuel pump relay. Splicing, seperating and re-wired correctly, the 240 is back purring. Thanks again for your in-put.

[vancouverbc]

Thanks for reporting back. What you say doesnt make too much sense to me which might just be my lack of experience. Power for the fuel pump relay comes from the ignition so if your car cranks you should have power at the pump relay. Another potential problem with your explanation is that your fuel pump came on for 5 seconds so your car should have started . I would also wonder why two white wire touching would be a problem.