Dont discount the fuel pressure gauge. It can tell you about the condition of your filter and your fuel. Compared to the boost and egt it also helps you determine how your engine is running. While running down to zero pressure in these truck is not the death sentence it was in a second gen it is still unclear just how healthy it is for the cp3, and some have died. The duramax and Euro 5. 9's that run sans lift pump have a different setup than you and your truck will not run without it. I have been working on these things all my life and when I walk up to one to try and figure out why its not running or not running right I always start with the fuel. I dont even think about anything else until thats had a look see. As an aside, am I the only one that would like to see an exmoniter with 4 readouts?