This is a new thread on the issue with low fuel pressure. The only time this drop shows is when the desired goes over 15K and then it drops to 3k psi. All PSI readings is being done with a TECH II. When driving the pressure goes up to 15k and when the desired calls for more it drops to 3k psi.
New Filter, New Regulator, Shimmed the FPRV, Checked the hoses between the filter and the pump with a vaccum gauge and it checked fine.
There has been several say the pump is the problem but I am trying to not miss something else the might be some what easier and cost a lot less. The pump is a job to replace and cost is $800 to $1000 for a reman CP3, unless someone can suggest one cheaper.

 

Are you sure it is not bad injectors?

 

at idle try and command 23kpsi, it should be able to do that, if it cant the pump cant make the power.

go over this, it might help.

https://www.dieselbombers.com/chevy-...ssure-side.htm

 

Oh sorry guys!! I had finished this repair on a different thread. It was the pump and IT RUNS LIKE A RACE TRUCK!!! It is so fast!!!! I had know idea that a diesel would just eat up these Z71's and leave them in the smoke!!!! LOL!!! I love it!!!!!