91 240sx hatchback fuel pump wiring problem

[dethatch]

my cars plug coming from the fuel pump housing was missing but wires intact. they do not match the colors going into the other plug coming from the chassis. I found the hot when key is on and I got the fuel gauge and low fuel light to work but the pump does not come on when I hit the key. I tested the pump (walbro 255lph) at the battery and it works. I get 12 v to the terminal going to the pump (until I plug the pump in the I get 0 volts with key on) the fuse is good up front. are there any other non obvious things that casue this? bad ground? can I just run it hot from the battery with a switch? or any suggestions? A wiring diagram would be nice for the fuel pump wiring. originally car was a 4 cyl n/a now its a rb25det. help! efi pump is good,fuse is good,pump is good,12v to pump w key on checked ok. what else?
Modified by dethatch at 6:22 AM 12/20/2009

[J14cm7]

The problem sounds like a bad ground or something shorting out the pump once it is plugged in. Turn the key on and touch your tester to the positve and the negative of your plug that plugs into the fuel pump. If this shows 12V it is def something that is grounding out in your fuel pump connector or something. if you dont get 12V your ground is most likely bad. As for the wiring diagram, there is an S13 wiring diagram on this site, just use that. Just because your car has a rb in it doesnt mean your fuel pump wiring diagram is different.

[dethatch]

figured it out, the pump was not grounded well..works now. Thanks