6.0l Engine Won't Start

[RM77MKII]

Drove a new (to me) 05 2500HD truck with a 6.0L engine 96000 Kms (60000 Miles) No problems except on a longer highway trip, some 20 miles non-stop. Hopped in a bit later and it won't start, cranks, but just feels like it's not getting any fuel.

 

I checked everything, went through every fuse, nothing out of the ordinary. Just for the halibut, I open the gas tank, reason to myself that maybe it's an air lock, or vacuum? The truck starts.

 

Happens two other times, same thing, always after a longer trip rather than hopping around the small town. It was suggested to try a new gas cap, I put a new one and can tell that the truck now starts like the other trucks I owned. With this truck it was necessary to hold the key longer as it just didn't seem to light otherwise, now just turn the key a bit, let go and it roars to life.

 

Thought the problem was gone, but repeated the 20 mile trip again and I couln't start it again. It will start, after opening the cap and waiting maybe 5 to 15 minutes. Now I don't even know if opening the cap was part of the trick that got it going again.

 

Any ideas what could cause this? Is there another place that must be vented? Is it fuel pressure that's a culprit? how can it be tested.

 

Thanks in advance.

[2017HD]

Probably something in the fuel rail return system - a pinched hose or something. This is the system that returns un used fuel from the injector rail to the tank. Venting the tank relieves the pressure in the line and everything works as it should - just an idea. In 07 they deisgned a returnless fuel rail.