Had the VP replaced 12 mos ago. About 5 mos ago one of the injectors was found to be leaking so I had it replaced. About a month ago I noticed the QUADZILLA COMMANDER showing fuel pressure dropping from 10 psi to 3-4psi then bouncing from 0 psi to 3-4, erratically. So, I replaced the fuel filter (I generally replace the filter on a regular 6 mos basis....probably overkill, but truck is worth it.
Yesterday the same erratic pressure behavior started again.... I have a RAPTOR 150 fuel pump, so I adjusted the flow upward a tad.
At idle, the COMMANDER shows a good steady 12-14psi. But as I begin to drive it, the COMMANDER shows pressure drops erratically anywhere from 0 to 7-8....continuous erratic fluctuations.

NO codes are showing (yet). Code DID show prior to the previous VP going bad.

Wondering if:
(1) I should replace all the injectors
(2) ...reallly hope the VP isn't failing...
(3) ...maybe the COMMANDER is going on the fritz...but it has been pretty accurate thus far

Thoughts? --D

 

oh, forgot. I replaced the fuel filter again this morning (WIX). No change in behavior. that's fuel filter change twice in 30 days.

 

If your system uses an electric sender style gauge plumbed to the VP, the sending unit could be getting ready to take the big dirt nap due to the Cummins 'shake'.
Might want to check it with a mechanical style fuel pressure gauge to be sure.