fuel system nightmare

I have a 90 chevy 1500 fuel system problem. It all came about when it would not start like normal! Got it running but had to keep it at very high rpm to keep it running. Got it home Changed the fuel filter and there wasn't even a sign that it was going to run! Changed the relay next and checked the fuse it was good. Went to start and it was the same...nothing. Next I changed the pump and strainer raised the tank hooked every thing back up and guess what...your right nothing! Checked for juice at connector which has three wires (bl/pur/gry) purple was hot with key on. Parts place said it could be a bad pump or the filter so I disconneted filter on the "in" side tuned it over and no fuel, so I said pump. They gave me a new one so I dropped the tank again and put the new one in and and the same thing again so I did some more digging and was testing the sending unit wire harness and had one prong out of the four hot which went to the float I'm pretty sure because that is where the two wires from that side go to. The other two go to the pumpand there was no juice on any of them two. I Do realize the pump is suppose to run when you first turn the key on but don't understand why I wasn't getting any juice the so I made another new product purchase....the sending unit. Before I put it in the tank I tested it to see if there was any thing different on the electical side of this sending unit and it was the same only one pole was hot! I even cleaned the ground up really good! what am I missing or doing wrong?

On my 96 the grey wire feeds the pump 12v. Can you find the fuel prime connector under the hood( a red wire sticking out of a harness with sime sort of connector on it. Put 12V to it and see if the pump will run or check for power at grey wire if sending unit is out of tank yet. There should be a splice for the fuel pump circuit under the hood for the oil pressure switch(it should power the pump if you have over 4 psi oil pressure)

Thanks for the quick reply! Guess what I went and got the third fuel pump an a/c delco this time because after I posted this I went out and did one more test this time I had someone else turn the key on and found that I had juice there it was that by the time I got back under the truck the juice had gone off all readyand was waiting to be turned over. With it hooked to the pump there was no noise what so ever. Put the delco pump in and turned the key on and I could hear it turn on and the next thing I new I had gas coming out of the fuel line. Sounds pretty good doesn't it...well now I've got fuel up to the carb but it still doesn't run! Would any one know what could be wrong now?

Do you have spark? Sometimes the pickup in the distributor goes bad/gets shorted during other repairs, and that causes no spark and no fuel pulses. That is where I would check next.

Thanks for the reply! I took the top off the air horn assembly and turned the key on, I had fuel every where! Removed the injectors, sorta inspected them set them back in and reassembled the horn and wala the darn thing started! Of coarse when I removed one of the injectors I riped the gasket so I will have to replace that now but at least it is running! Thanks again to you two for your replys

well guess what got new gasket rebuild kit put everything back together and it would not start! Seen an artical on a web site and it metioned clamping the return line to build pressure so I did and it started up and ran fine. would it be the pressure regulator (spring) I already put the diaphragm in with the rebuild kit or something else?

help!