2.9l giving me a headache

[Pix3L8]

Spent a few hours cleaning every engine ground and PCM ground I could find. The result is my rear defroster now works again but everything else is the same. Will report back later once I test more of the electrical harness.

 

[Snoranger]

It definitely sounds like a computer issue. Try testing with the alternator disconnected... I’ve seen stray A/C voltage cause all sorts of untraceable issues.

 

[Pix3L8]

update for you guys: im still trying to figure out this PCM or electrical issue but as some of you pointed out the fuel issue needs addressing too. I went over to the parts store and snagged a fuel pressure regulator. With the new regulator, the truck idled at 25psi, I'm assuming this new reg is bad. I put the old one back on and I'm back to 29-30psi at idle. However im still noticing a pressure leak after I turn the truck off, the psi will creep up to 34-35psi then over the course of an hour drop down to zero. I put in a new fuel pump and injectors this year. From my research last night on this return style efi system I have 3 possible leak points.
1. check valve in the pump assembly
2. injectors
3. diaphragm in the FPR

I am assuming that because both the new(bad) and old FPR gave me the same results as far as this pressure leak I can rule them out for the time being. I can also assume that because I have a new pump that is not my issue. now look, I know that replacing a part DOES NOT MEAN IT IS FUNCTIONAL, again this is just an assumption with very minimal diagnosis. I am assuming the pump is not my issue as I had THE SAME ISSUE with the old OEM pump but I will still test it. I need to pick up a set of t-fitting adapters for my pressure gauge and I have a new Schrader valve for the rail on order. Once I get these in a day or two ill continue to look into this.

my testing process will be as follows (let me know if this is logical)
1. use my gauge and t it into the pressure line so the fuel cannot return to the tank.
2. power up the fuel relay to deadhead the pump for a split second, this should allow me to isolate the pressure side only. if I don't get a pressure drop off then my check valve in the pump is working correctly.
3. connect my t to the return side of the line after the FPR and block off the return line after my tester again to test for leakage. If I am still seeing a leak then the ONLY place it could be going is out an injector (assuming the pump checks out OK).

Besides pulling the plugs and going in with a borescope I'm not entirely sure how to test which injector is leaking (if that ends up being my issue) because this isn't OBDII and I can't really break out the laptop. I assume I can look for an open ground in the injector harness which would mean a PCM issue but I don't think this will be my issue. If I cant find an open ground then I would assume that I have an injector that is mechanically stuck open......remember cyl 4 I talked about earlier with my sooty spark plug....hmmmm....the pieces are coming together now.

this is the method I think will work to diagnose my fuel system but let me know if I'm overlooking something. For years you guys have been saving my *ss on this truck so I'm curious to hear feedback.