[J Young]

I have a 99 sierra 2500 6.0L, I noticed it had some trouble starting, so I replaced all the plugs, wires, and fuel filter. It still had the same symptoms, I then did a fuel pressure check and the pressure was 45 psi with the key on and 48 psi with the engine running, I unplugged the vac. line to the regulator and the pressure went up, so I knew for sure it was the pump. I used my engine hoist to tilt the bed, it was alot easier then I thought, I hope this helps out some people.
Jeff

 

[Revredneck]

Congratulations on getting it done. I'm getting ready to change the pump on 03. By the way, the fuel pressure is supposed to go up when you disconnect the vacuum line to the regulator, usually about 8-10 psi.
Good Luck and God Bless