fuel pressure doing something i dont understand

[djamesp]

Long story short anytime i crack open the throttle my fuel pressure sensor pegs to 130psi+ (i dont have the transform set up exactly right, so the numbers may be a little off) then drops/bounces all over. The only thing i see thats unusual is that my fuel pressure chart line is absolutely identical to my wideband AFR line, see log at 4:30 for a good example. Was not like this before, truck runs like garbage all of a sudden. Just hoping someone brighter than myself can look at this and give me an idea what could be up here. I assume its a hardware issue not tune related but I dont know what would make pressure jump up like that vs drop (failing pump, clogged filter, etc). This is an 06 LM7 in a 03 silverado single turbo. fuel setup is a walbro 400, inline filter i cant remember the brand of, stock rails with deka 80s and an AEM vacuum referenced regulator. pressure is dead-on 58psi at idle with the vac line unhooked, according to my manual gauge. And, if it makes any difference fuel pressure and wideband share the same ground off the prolink connector.

23-11-27 22-47-44.hpl
RCSB V3 - 4L80 - 2BAR RTT - Copy.hpt

Any advice appreciated.

[blindsquirrel]

Does the mechanical gauge show it going to 130? Do you have any fuel in the vacuum reference hose to the regulator?

[djamesp]

Cant tell for sure on the mechanical, its mounted on the rail and it only does this under load. If I can't figure it out an easier way Ill run a line into the cab and check again. No fuel in the vac line. I'm sure its changing because the way its running changes when pressure goes up or down on the chart but it'd probably be blowing stuff apart if it was really cracking 100+psi, wouldnt it?

[blindsquirrel]

If you're doing your own work on EFI systems you must have a mechanical fuel pressure gauge, like the diagnostic tool style, with a long enough hose so that you can snake it up through the rear of the hood and see it from the driver's seat. The rail mounted things are pretty useless if you can only see it while parked with the hood open.

[djamesp]

I see that now haha will come up with something. Finally had time to play with this again, went out for a drive watching the fuel pressure doing the same thing except I had unplugged it to fit a different gauge. So no sensor hooked up at all on the red prolink connection but its reading the same as the blue wire connection? From the shared ground maybe? This just started out of nowhere, was working fine for months before.