Fuel Pump Help Needed!
 

I have low fuel pressure - below 20 on a 1990 Cherokee 4.0. I pulled the fuel tank. There was a lot of mag. Took the fuel pump out, ordered a new one from Rock Auto - Delphi brand. Put it in the clean tank, replaced all inlet/overflow lines, put tank back in , new fuel filter, went to plug into plug and the color code is backwards. The black wire is on the positive side. The positive wire is on the ground side. The gauge wire is gray. It can only plug in one way. Turned the key on, tripped the relays - got nothing. I took the tank back out. Ordered another pump off ebay, tank is back on the work bench 3 weeks later it gets delivered the plug is the same black wire to hot, positive to ground side...won't work. Phase 2 - I took a clean 5 gal bucket with 5 gal of solvent in it. Submerged the original pump in it with ground wire hooked to it, and hooked the positive from a battery - one gray, one orange, it pumps away great, but holds no pressure! Pump #2, the Delphi, put it in the bucket grounded the pump hooked up the positive which is now the gray wire. It sounds like it's working, but won't pump anything. Pump#3, did the same as pump #2, and won't pump one drop of fluid.
I have 3 Jeep Cherokees '90 Laredo, '92 Limited Edition, and '95 Countryman. I have put them all on the hoist, and the wiring coming from the car to the pump is orange is hot, black is ground and gray is for the gauge.
The wiring on the pumps are backwards. I have spent all this time and wasted time and money. Any suggestions?
I sure would appreciate some input!

If that truly is the issue, can you not cut the wires and splice them into their correct positions on the fuel pump side of the wiring? I'd recommend whatever reasonably priced pump has the best warranty, although if you have to change the wiring that may void the warranty.

Thanks. There was a splice kit in one of the pump boxes, 'cause it could be a GM product, too. Just seemed counter intuitive.