2006 f350 super duty 6.0 starting problems
 

Turned it off for a couple of minutes wouldn't start. Let it cool for 15 minutes tried to start and it hesitated but did start, only happens when warm. Has been hesitant to start 2 times before, wouldn't start once so far. Any opinions?
No mods, we use as a Hot Shot truck. We have changed fuel filter in the last month.

How many miles? Any work done recently or did this just start out of no where? Basically it starts fine cold, but has issues restarting if the motor is still hot right? Probably a high pressure oil leak. What happens is the low pressure oil feeds the high pressure pump, the pump bumps pressure up and hydraulically fires the injectors. Eventually o-rings will fail, or quite commonly the STC fitting on the HPOP will crack. When the truck is cold, the oil is thick so it can build pressure and start easily, as it warms up and thins out, it will bleed out of these leak areas and wont allow it to build pressure.

Do you have access to some sort of a decent scanner? Something you can measure ICP (injection control pressure) on?

It has almost 200,000 miles now. Might be able to get mechanic down road to put it on his scanner. Where should he start looking for leak? It just started last week first time. We change egr cooler and oil cooler in June of this year. We change oil and filters every 5,000 miles. We even cleaned out the turbo exhaust pipe last month.

It's not going to be something you can just "see" per say. First place to start is if you can get it on a scanner, measure ICP desired vs. ICP actual and also check IPR duty cycle.

ICP is the pressure that is coming off of the high pressure oil pump. ICP desired is what the PCM is telling the HPOP to put out, and actual is what it is really doing. IRP is the valve in the back behind the turbo that controls the pressure. If ICP desired is way higher than actual, then you probably have a leak. There is also a way to test this mechanically as well, if you'd rather do that.

Are there any codes being thrown at all? No check engine light?

His hand held isn't showing any codes. No check engine light. Should he take it to Ford dealer or would a shop with a good size scanner work? He just told me he his last tank of fuel was some kind of bio-diesel ( he doesn't run that at all in his truck) He want's to know if that could cause problem. He says the fuel pump isn't whining either.

Depends on the biodiesel... someone's home brew creation or he bought it at a pump? If it was someone's home brew it's probably B100 or close to it, that stuff will strip the inside of a fuel tank quick. It's not a bad thing, but something that should be known. I would highly recommend changing the fuel filters on it, I bet all the gunk in the tank is on them right now.