I have industrial injections dual cp3s with a stock cummins pump with a stock duramax pump above it. When Im driving on the road if I go WOT my rail pressure drops down to 6,000 psi and doesn't come up above 10,000 psi til I lift off the pedal. I talked to some people and was told to check each FCA individually by unplugging the FCA and checking the rail gauge, if the FCA is good the rail pressure will come up to full pressure. So I unplugged the top pump FCA and rail pressure went to 27,000 psi. Unplugged the bottom pump FCA and rail pressure also went up to 27,000 psi. So I called Industrial to ask if they've had problems with the electronics, they told me it was the probably the releif valve. So I put a rail cap on it a little bit ago and no difference. I don't run the Dr. P box on the road, but I did flip it to kill at WOT and rail pressure didn't increase any. At normal driving the truck makes 17,000-22,000 with the Dr. P on it will go all the way up to 29,000 but thats just normal driving not WOT.
The rail pressure is set on 2 the smarty currently.