Pinch the return line off and see if the pressure builds then rev the truck and watch the gauge to see if it falls. No fall bad ofv if it does weak pump

so i pinched the line a little bit and the fuel pressure was still around 10psi at idol and then went up to maybe 25 when i pushed to 3500rpm, i then pinched it all the way and when i got on it, it went straight to 0??? maybe just somthing i did wrong, i replace the lift pump around 5yrs ago with a new one from Pensacola Diesel, the outlet line was a bit differnt hook up so i had to rig up so home depote brass fittings, hose clamps, and fuel hose, maybe thats my problem???

167's and 131's are the same.

ah i see, whats your guys opinions on the 4 hole 90hp injectors? i know of another set i could get and swap them out but they are really big supposebly, they came off a truck done by A to Z Diesel here locally in mesa, the tech that pulled them said they were too much but im wondering if they were too much because he was also running a race p pump and completely built motor and a different cam. he has like 18k into the motor build to give you an idea of whats done to it

so i was online looking at performace parts for the p-pumps and found new delivery valve holders that are much bigger than the stock ones, they are the things that you need a special socket to remove and the new ones are six sided not splinded, my question is-i thought they were shimed and fit to a paticular barrel??? or are the spring things inside are whats shimed to each barrel?