Fuel problems need help

[blakeh]

My 98 Z71 just died as if it ran out of gas, but i have plenty. It wont start anymore but i noticed that the loud whinning from the fuel pump is no longer present when i turn the key forward. Is this problem the fuel pump or another aspect of the fuel system like the injector etc..?

[Llogoaero]

First thing to check is the fuel pump fuse and if I'm not mistaken you have a fuel pump relay.Go to your local library and check to see if they have a service manual or chiltons for your truck.Look in the back for a wiring diagram of the fuel system and it will tell you if in fact you have a relay.If you do you might be able to bypass it and see if the pump runs.Keep in mind that alot of GM vehiclesnow have the fuel pump and fuel sender as one part and even though your gas guage is working fine you end up changing the sender as well as the pump which I had to do on my truck and ti wasn't cheap.
Good luck

[dirt49er]

chech the ecm b fuse, thats normally the one that will fry, chech the wires that run along the frame for the fuel pump, sometimes they can get pinched on the crossmember for the tranny

[JC_98Z71]

Blake I have the same truck and the same problem. I don't think you need to be alarmed if the whining sound isn't there after the you turn the key forward. Once the fuel pump primes the engine once, it doesn't do it again until the engine turns over and stops (you can hear the pump dumping the fuel back in the tank).

When I took my tank off, I left the fuel pump on (couldn't find the right quick connector release) and put it into a small bucket of fuel. The thing worked just fine. It wasn't as loud as it usually is but it seemed to pump just fine. My truck ran like a champ. I changed out the fuel filter and fuel screen on the pump and put everything back together. I put the key in and heard it prime, but damn thing wouldn't start. I'm just baffled. The only thing different that I know of was the fuel pump wasn't compressed while in the small bucket. Anyone got any ideas?

[Jeremy-WI]

The fuel pump should energize for about 2 seconds when you turn the key on, unless a crank signal is received by the PCM and then it should keep going. You should do a fuel pressure test to see if the fuel pressure gets to spec(60-66psi, key on engine off). GM says it takes 40 psi to open the poppet valves and under 55 psi you are guaranteed hard starting. If the pressure drops after the pump shuts off redo the test with the return line crimped at the rubber line section between the engine and the fuel filter(return line is not the one with filter-clarification). If the pressure holds with line crimped replace fuel pressure regulator

[BOSS222211]

THANK YOU THANK YOU all of you a gas station tried to charge me 750.00 to put in new fuel pump in 02 z-71 . He said he checked at the pump and it had 12 volts but i just couldn't believe he got up there to test it without moving or unbolting something. Thanks to you all i found the problem myself A simple fuel pump relay borrowed from the headlights was switched and the damn thing spit fuel all over me as i was under the truck. I have to say it was the best damn tasting gas i ever had thanks again roy