GM-GMC: no fuel pressure., fuel pressure regulator, chevrolet pickup

Question
I have a 1997 chevrolet pickup with no fuel pressure, have changed fuel pump and fuel pressure regulator.  If prime with gas will start for few minutes and quits. don't know what else to do please help. have replaced fuel pump twice

Answer
Rhonald,

  Its important to test for both Power amd Ground at the fuel pump connector, if there is not power or ground going to your pump it will never run no matter how many pumps you change. Don't worry if you can reach the plug on top of the tank, look for the wiring harnest coming out of the tank and follow it towards the front of the truck, somewhere around the fuel filter it should split into a connector, this is where you can test! Use a Test light or if you rather a Voltmeter and get yourself a helper to work the key. Get yourself a wiring diagram if you can, if you can't I think the fuel pump power should be the "Grey" wire or the "purple" wire and the ground will be "Black". Most GM are wired this way! There should only be 4 or 5 wires in the connector anyways so you could always just "Look" for the following. Try the Gray wire on the engine harnest side. with the test light or the voltmeter to a good ground. I recomend getting a long jumperwire and going straight of the (-) Batt. terminal. Get your helper to turn the key to the "on" position(all dash lights on. You should have a Power (12+) Volts for 2 seconds and then it should go away, this is to prime the fuel rail. If you don't find this perticular wire try the other ones till you find it. Keep in mind that the key needs to be cycled everytime you try(to off posiyion for 5sec. then back to on position. If you find this power get your helper to turn the key to "crank" and hold it there while you test. The 12+ Volts should be back and stay there till you stop cranking this is the constant power to the pump. If you have power then try for a ground. Hook the other end of the test light to Batt (+) this time and probe the black wire your test light should light indicating a good ground all the time with key on and in the crank position. If both of these are present then you have a faulty pump or wiring to the pump and it will be nessesary to access the connector on top of the tank and repeat this test there. If you are missing either a power or a ground your into trying to figure out why the pump is not being "Fed" the missing +/-. One common problem is the fuel pump relay, this one is easy just locate it, probablyin the engine compartment fuse box and then pull out an A/C relay or a ABS relay, make sure they have the same pin configuration as your fuel pump relay and simply switch the two. I the truck starts but now you A/C won't work or you have an ABS light on in the dash you've got a bad relay! Hope this helps!