My 2003 2500HD 6.0L Gas engine truck died while I was driving it on Friday. It was towed to a shop and the mechanic told me it was the fuel pump and it would be $800 to replace. I bought the part myself, dropped and drained the tank and replaced the pump assembly. I put about 6 gals of gas back in it, but it will not start. I removed and emptied the in-line filter and replaced it. Still no luck. Am I missing something? What else do I need to do to get this thig started again?