I've had the truck to the dealer to have the lift pump tested and they say it is within spec. Rail pressure never dips indicating it is not getting enough fuel. Do you think the FP unit is bad?
Thx

 

I don't guess I understand that?

Check the installation of the sensor on the FP side. Make sure you did not use a ton of teflon tape, that can cause the sensor to not get a ground and it won't work.

 

It worked fine for the first 8-10 months after it was installed. I will check the grounding of the sensor, but I don't believe that is an issue.

I was under the impression that if the lift pump is going out and starving the CP3 then the rail pressure would drop randomly as the CP3 runs out of fuel. Is this not correct?