i just installed a FASS fuel system a month ago because i started lossing fuel pressure at 108000 miles. truck still starts great so i'm thinking the fp is fine. it ran better than ever until a few days ago. it use to boost up to 32psi quick with lots of power up to 3000 rpm ,now it falls flat on it's face right around 25psi and it strugles from 2200rpm to 3000rpm. only mods i know of for sure are wastegate elbow and boost fooler. it had a edge ez but old owner took it off, he also said it has 150 injectors. i had a friend with a ecm reader test drive it. it was giving a over boost code. the strang part is that my new mechanical boost gauge was showing max boost at 26psi but his computer was showing boost at 41.6 psi. we then naticed that when the truck was not running that it was showing 11.9psi.?????? it also was picking up the cam sensor but was not getting a reading. i need this truck but i don't know what to start fixing. thanks for any thoughts.

 

Welcome to DTR -

A few quick things to try -with the flat spot in your rpm band, you could do an apps reset; Sounds like your boost gauge needs a "re-set" as well, is there an adjustment screw to re-zero it? You should check the cal on it as well - the null at around 12 plus the 26 psi indicated is 38 psi, reasonably close to your friends reading of 41 psi.

Run through the air and fuel filters, make sure they are good. Clean the IAT and MAP sensors; Do you run any additives - your injectors may not be performing in an optimal fashion? What are the FP and pyro readings doing, anything changed with them? The FASS will probably take care of FUTURE FP issues, but the old pump may have put the hurt on your VP44 - from reading your post again, it doesn't look like you have other gauges?