In the scan tool when you are hooked up you can alter the fuel rail pressure (might not be exact but you all know what I am referring too) and injectors on and off as a diagnostic tool. What exactly is that fuel rail pressure (or whatever its called) control? I am currently experiencing issues with my cp3 (when accelerating the desired fuel rail pressure is not even close to the actual fuel rail pressure) Example... I was hauling a load back from Nebraska last weekend and the desired fuel rail pressure was 23,XXX psi... the actual was reading 5,XXX psi. Driving unloaded today I saw a desired of 18,XXX psi and a actual of 7,XXX psi. So as I am trouble shooting I try to change the fuel rail pressure (or whatever it is in the scan tool on the injector page) no matter what I adjust it to, it never changes anything... and everything is activated and turned on and what not. I can then move over and alter idle speed with no problem. I also noticed that throttle position is stuck at 50.2% no matter what on the view graph page, but on the dashboard it shows 0?? anyone see this?

In the scan tool when you are hooked up you can alter the fuel rail pressure (might not be exact but you all know what I am referring too) and injectors on and off as a diagnostic tool. What exactly is that fuel rail pressure (or whatever its called) control? I am currently experiencing issues with my cp3 (when accelerating the desired fuel rail pressure is not even close to the actual fuel rail pressure) Example... I was hauling a load back from Nebraska last weekend and the desired fuel rail pressure was 23,XXX psi... the actual was reading 5,XXX psi. Driving unloaded today I saw a desired of 18,XXX psi and a actual of 7,XXX psi. So as I am trouble shooting I try to change the fuel rail pressure (or whatever it is in the scan tool on the injector page) no matter what I adjust it to, it never changes anything... and everything is activated and turned on and what not. I can then move over and alter idle speed with no problem. I also noticed that throttle position is stuck at 50.2% no matter what on the view graph page, but on the dashboard it shows 0?? I would bet that you are simply scanning the wrong pid. use a different TP pid and that should fix your problem. anyone see this?

As for the rail pressure problem....

Are you running a mild - medium pulse width on your tune? If so i would start by changing your fuel filter! that seems to be the culprit behind all rail pressure problems. If that doesn't fix it i would definitely look into a lift pump of some sort.

I change my fuel filter regularly but I will change it again just to be safe. I run a fass 150 setup thats keeping roughly 15 psi going to the cp3. (I run a fuel pressure gauge). I am not sure about what the tune's pulse width is, all i know is its the +30hp tune from duramaxtuner.. just as a fuel economy/tow tune. I will do some more research.

hmmm.... i would not expect your symptoms with your setup and tune. that does sound a little like CP3 problems.