Here is all the information I have. 2006 4wd 6.0l powerstroke 103k miles I'm having a problem starting the truck on occasion, sometimes it fires some times it doesn't, i have knowticed lately that sometimes with the key on I can't hear the first priming pump (or what ever pump you can hear cycling with key on) if you cycle the key some times it will kick on, but back off before the glow plugs cycle, if the pump stays on past the glow plug cycling the truck fires fine. the circumstance doesn't seem to effects the randomness of the prime pump coming on or not cold, hot, low fuel, full fuel, truck warmed up, cold truck nothing seems to effect it. And another problem may be related is when the truck is cold it doesn't seem to have much power( I don't step on it with the engine not to operating temp) the truck just seems to lack usual power, the lack of power has been around for 1-2months. Other than the lack of power and starting issue the truck runs great pulls great just don't shut it off and you don't have any problems. Here is what has been done so far, batteries have been replaced, ficm has been tested by a shop showed proper volts, fuel pressure regulator was leaking fuel so it was replaced,fuel filter changed, and pulled the H.O.P sensor and tried to start with no luck starting every time. that's all been in the past 6 months Ish and I can't seem to find a shop that can figure it out so I thought I would give it a shot I'm very mechanical just don't know much about diesels so any input would be greatly apprishated.