Fl cowboy

Any luck yet?  

Is it and LBZ (classic body style) or an LMM (newer body style)? 

LMM has (or had) the diesel exhaust filter (DPF)

What's it history? Is it 'tuned'?

How many miles on it?

What has already been investigated?

Do you have a way to monitor fuel rail pressure signal? 

Low all the time or just at high engine load? 

Might just be a pressure sensor or fuel pressure regulator. 

Has it been to a knowledgeable diesel shop?

Sorry about questions but a lot of things can happen over 15 years.

New motor put in truck with 140000 miles on it came out of a very clean truck heard it run before put in my truck change a supply line that comes from tank on suction side it was thought to be collapsing under load  idled at 4300 psi on fuel rail with computer when coded are cleared and watching live data on psi rail pressure the most I have seen is 12000 psi then throws code and is derated 

Was told by the guys that installed motor this code was in computer on old motor as well so I am thinking that it is something truck related took air and gentle blew back through the system from the filter base and still does same thing have been thinking of putting a supply pump inline to supply the cp3 pump is my next step I am thinking