2000 GMC Hard Starting

2000 GMC 5.3 My problem is similar to other post. I replaced the regulator, fuel pump and filter with all AC DElco. In the morning seems to start ok. Still hard starting after setting 15 min. or so. if you turn key on,off,on then will start. Trk runs fine. I put a gauge on the rail, when the key first on 60 psi but drops to 0 fast. When you start psi is 60 then drops and holds at around 50psi. Any Ideas.

You may have gotten a bad fuel pump - should be under warrenty. Either that or you have a leak in a fuel line somewhere.

Put the fuel gauge on it, pressurize the system (have someone turn key to on), then pinch off the fuel supply & return lines. If pressure leaks off, you have a bad injector (but you said truck runs fine, so prolly not the case).

Then do the same thing pinching off the supply line only. If you have leak off, then bad fuel pump check valve or leak in return line.

Pick up a Haynes manual. This process is described in detail in addition to other process of elimination tests.

Also try replacing your fuel pump fuse.