Fuel Pressure Leak?

[GMC2002Sierra]

2002 Sierra, 6.0 liter Vortex, 125,000 miles: Fuel Pressure (KOEO) is 65 psi when pump is running (the first 2 or 3 seconds after turning the key on) after the pump stops running the pressure drops to 0 psi. With engine running the pressure is 55 psi with the fuel pressure regulator vacum hose connected and again to 65 psi when I disconnect the vacum line to the fuel pressure regulator. The Chilton's manual tells me that the fuel system should stay pressurized and drop no more than 5 psi in 5 minutes after shut down. I am supposed to suspect a fuel injector leak, fuel line leak or fuel pump module check valve. I just replaced the fuel pump module and can't find any leaks in the fuel lines, how do I check for a leaking fuel injector? Any other possibilties?

[GMC2002Sierra]

I figured it out, I had a leaking fuel pressure regulator. The regulator is working fine (hence the fuel pressure rising once disconnected) but the inner 0-ring was damaged and letting pressure leak off.

[TexasAl]

I just read your original post, and I was about to suggest the fuel pressure regulator. I'm glad you got it worked out.

 

-Al