90 psi fuel with eng stumbling,bad injector or injector o rings

[chubacabra]

Hello there guys new to the forums and diesel.I have been doing some
research on them after buy this f450 and there has been a lot of helpful
old topics however I could use some advice.99. 7.3 powerstroke

I have done everything that I know off to the truck other than crush it.
Icp sensor replaced,leaking.Ipr replaced and ipr pigtail.Next I have tested the icp pressure while driving 650 at idle,in neutral wot at 1400 and wot while driving is at 2400lbs. Fuel psi for some weird reason is now at 90 lbs. I have done tried two differnet liquid filled gauges may'be I have a bad gauge.While your driving as long as your foot is in it psi will stay 90lbs while coasting it will rise to 120lbs.Truck still is stumbling every now and then eractically and goes back to great running condition.Their is no codes for anything now wondering if it could be a bad injector o ring or a bad injector sticking open causing cylinder psi to enter the fuel system.So if anyone can think of somewhere else to look or test I would much appreciated....

also to add camp sensor is good and wiring done looked their

[timmyboy76]

where you read'n fuel psi? At the fuel bowl, if so, pass side of bowl or driv side? Inspect the filter, does it look oily? If so, then the added psi could have blown an oring or two.

Possible, the fuel psi is caused from the FPR sticking. Had that happened to me. I removed the plunger, and wet-sanded the high spots on plunger. Re-installed, alls good.

[chubacabra]

I'm reading the psi from the driver side top port,also the fuel bowl is full of clean fuel.I have also done inspected the fuel pressure relief spring assy,it is fine.Btw I did snap off the fitting on fpr,those are some delicate threads.

After letting it sit for 6 hrs,went back out driving went half a mile and
psi dropped down to 30.I'm just fed up with this,fuel pump is new and I have done replaced the lower pick up feed tube in the tank. I'm just going to
run it out of fuel can in the morn with a new line feeding up to the fuel bowl.
But I don;t think their is air getting into the lines cause when the cap is off and ign switch is on the fuel bowl is filling up with fuel but their's no air bubbles in the bowl

[timmyboy76]

your reading is pre-filter. p/s fitting, is where i would take reading..post filter. Possible, your gauge is goofy. Try hooking up a manual gauge and see what its bang'n at b4 throw'n $$ away...

[chubacabra]

I found that my gauges were being corrupted by my test gauge hose was seperating on the inside Replaced with new hose, tested psi down now on the pass side back to normal psi at 60lbs. I remembered that the code reader was showing codes for trans input,solenoid etc,why would this go on with a manual.

I removed the pcm and found out that its an auto pcm,so it made me think which is kinda dangerous.I had the old ipr pigtail I went ahead and extended the wires routed the power wire to batt pos and neg.Crank up Icp psi was topping out at 3600lbs before popping off.I just went ahead and took unit out on a test drive,studdering is gone. I'm just thinking its in my auto pcm is in need to be reflashed with an man version. Has anyone else had a similar problem with a auto pcm in man truck with it studdering at lower rpm;s eradically while trying to accelerate.