2004.5 F250 SD XLT 4dr 6.0L
CAI, 4" Straight exhaust
EGR Delete, 6.4 Injector pump
Coolant filtration system.
New injectors al around
New ICP, New IPR, New Oil Cooler.
Recently Bulletproofed on ARP head studs, and the stock Head gasket,
New injector harness and FICM from DieselTech Ron
SCT tuner, running innovative diesel tunes. EGT Sensor
37x13.5r18 nitto trail grapplers

Truck started bucking and stalling. No codes. FICM and harness are new and plugged in correctly. TPS is new, CPS is new. MAF Cleaned [not throwing a code. All the sensors were checkked and the wires checked. nothing is chaffing or unplugged. ICP is new, Recent head rebuild etc. Most of the injectors are new, and if one was bad, it would be throwing a code or a contribution error according to what everyone on the forums and the ford dealer have said, plus I recently had them all electronically teste when the heads were done. [could be loose under the valve cover though, i have read that situation could cause my issue without throwing a code...]

When i did the blue spring mod a few weeks ago, I swore it actually made it worse. now weeks later, it starts stalling and bucking like it is fuel starved. If it starts, i just let off and wait a sec, or if it stalls, i just have to turn it on and off so the pump runs a few seconds and it fires right up. I did the filters and tightened the hoses near the upper fuel filter and it got a little better. Got a cap and PSI tester coming in a few days.
If I hit speeds over 50 or so, it starts bucking no matter what.

I can hear it hissing after I shut off the truck. Coming directly from the upper fuel filter hosing. [this normal?] no leaks though. Could this area suck air in? That may explain why at highway speeds, i get the issue but not as much at lower speeds.

Once I get the fuel psi cap and tester installed, How do I determine if there is an issue? What if its getting the requisite 48 psi at idle but not at highway speeds?
What else besides fuel could be causing it? I guess I could have killed an injector again, but I have had bad injectors and a FICM die. It didnt buck and stall with a bad injector, it just ran like crap. This thing runs great until it doesn't. Just like that. then it runs great again. I have a Tuner that monitors everything. I have read about and tried monitoring just about everything but Fuel PSI. Its all normal. Truck still bucks and stalls at highway speed =[

 

the blue spring is designed to keep fuel pressure above 50psi and dropping. usually what happens with the factory spring is fuel pressure will be at or above 50psi and when you step on the pedal it drops. this causes the fuel cups in the injectors to not have enough fuel in the cup under fuel throttle and damages the plunger and internal parts in the injector. now there's a couple things that can cause this.. but usually when your fuel pressure drops it doesn't buck. first I would check icp sensor. if you can watch it while driving and if it spikes it will cause bucking. another thing could be ebp sensor. there is a fuel pressure test port on the front of the fuel pressure regulator. you can hook a hose to it if you have the right adaptor and while your driving you can watch fuel pressure.. another way is with an aftermarket fuel cap that has the 1/8" test port on the top. either will work. look at fuel pressure at idle and while under full throttle. if it stays above 50psi your good.

 

I have a test adapter that just arrived. I ended up finding a piece of an injector inside my oil pan. A small screw that attaches the Tubular body to the electrical components at the end of the injector at the head. Assuming the injector nut that was attached to my pan bolt was indicative of a bad injector, I pulled them all out and inspected. Turns out every one of them was whole and complete, working fine. o.0. This part must have come from a separate repair done years previously... or something... Either way, when removing the oil rails. I noticed one of the stand pipes was broken at the neck. I replaced the pipe and the dummy plugs today and I am also cleaning and replacing the oil screen in my IPR while it is easily accessible. If this does not do it, i give up and I am never buying another ford/mercury product again. Pretty sure the broke stand pipe should be the issue. Fingers Crossed

 

Broken stand pipe would almost certainly cause inconsistent oil pressure and bucking.....no hot start issues mentioned tho and that should pretty much certainly be an issue.
Any updates on your problem?

 

stand pipe was it. No start issues probably because the rail was only partially inoperable. The pipe was in place but cracked at the oil rail at the very end of the system , so it was only affected at high rpm. Trucks runs great now. Cost me $90 to fix it. I guess most oil issues usually occur close to the pump, causing start issues. My issue was so rare it was undiscoverable without teardown. Shop would have charged me thousands..