I have a 98 Suburban K1500 With the 5.7 and I am having fuel problems. What's going on is that when I shut it off and try to start it, it usually will sputter and die, and refuse to start unless I wait for about a minute, after which the fuel pump will come back in for the 2 seconds before starting. It also has died will driving and at an idle. I have done a pressure test and when it happens it drops to 0 psi. I have swapped out the fuel pump to a brand new Delphi pump and the relay is brand new and it is still occurring. Where should I go from here?

 

What is the idle RPM? If it's low, 500 rpm or so, suspect the regulator.