Fuel pump not priming
 

Hello all,
I have a 1998 C1500 4.3L. I replaced the fuel pump about 2 years ago, and some time after replacement, began having issues with the pump not priming (Or so it seems). I could get in the truck, turn the key on (not over) and hear the fuel pump make a high pitch noise. I turn the key over, and the motor will not start. I turn the key on and off until I hear a low pitch noise from the pump, only then will the motor start. Seems to me like the high pitch noise means the pump is not priming, and the low pitch means that the pump is moving fuel.

Now, 2 years of occasionally having the low-pitch noise (and no start) occur, the pump will not make the low pitch noise at all, and the truck will not start. I replaced the fuel filter, and no help.

There is the valve on the fuel rail, I pushed it and removed pressure from the rail, turned the key on and off, and pushed the valve again, there was pressure, but mostly air.

I am about to go add fuel to the tank, even though it should have plenty of fuel, and if that doesn't work, I plan to remove the pump and inspect it. I am hoping to not pull the pump, because it is a PAIN to get it back in. I am hoping I can get a better suggestion.
Thank You,
Jbob02

You say you replaced the fuel pump 2 years ago. What brand of pump did you use? If you bought a cheap off brand then it is probably bad. The check valve in the fuel pump assembly is letting the fuel drain back into the tank. When doing a job like this it is not worth using the cheaper ones because they will fail in a short time. It is best to use a Delco or Delphi pump.

What is a suggested way of checking the check valve? Just using a pressure gauge at the fuel rail?

If you have to crank the engine for about 10 seconds or so to start it then it is a good bet that your check valve is bad. When I had that problem I added a check valve in the fuel line and that solved my problem. The truck started quickly after I did this and I didn't have to replace the pump.