2005 Ford F350 Diesel f350 superduty automatic 1 ton duly f

HI STEVEN, powerstrokes are very complex engines. This could be many parts. But you will need to get truck scanned. This will give you an idea. Could be crank sensor. Could be cam sensor. Check oi; make sure proper level and clean. Oil is very important in this engine. As this is how the fuel system works. It could be a high pressure oil pump prob. So see without the scan of the pcm. It would just be a series of expensive guesses. Good luck billymac

Have a Ford shop check Injection Control Pressure(ICP). If the IPR(injection pressure regulater) goes to max. (85%) and ICP still can't get to 500 psi (min.) The pcm will not enable injectors (to electrically open the spool valve). They will then put air pressure in the high pressure oil system and command the IPR valve to move - listening for a change with a stethoscope in thier favorite spot.
If NO CHANGE is heard they'll remove ipr and inspect. If visually ok they'll replace it. If damaged it needs the screen under the engine oil cooler in the front of valley and HPP(high pressure pump)replaced -the screen melts(it's plastic) and ANY/ALL DEBRIS GOES THROUGH PUMP. It's a good idea to replace the EGR and oil cooler while you have 'em off also. Otherwise just replace the IPR but keep fingers crossed.
If CHANGE IS heard they'll start looking for the leak - can be elusive! The Ford/Navistar by-the-book method works well IF you've all the special tools. Failed O-rings in oil rail "dummy" plug, injectors, HPP outlet "quick connect" fitting, even "branch tubes" are all VERY COMMON. (It's usually the last place you look) ALL of these are hard to get to!