GL450 Won't start sometimes

[POLONASH]

I have a 2007 GL450 with 58000 miles that won't start some of of the time. Starts fine in the morning. After using the car it will start after sitting for a short time (20 min or less) or a long time 2+ hours but not in between? It will turn over just fine. The battery is strong and the starter works fine. It seems like its not getting gas. It'll try to come to life and rumble on for a couple of seconds then dies. I can try this 20 times to no avail. Any thoughts on what may be causing this?

[POLONASH]

I just wanted to add that I don't have a check engine light warning.

[eric242340]

Possible crankshaft position sensor, when this gets warm it tends to fail but works ok when cool. If it does not send a signal then the fuel pump will not turn on.

[POLONASH]

It's at the shop now and it's not the crank sensor. They're looking further into it. The mechanic says its losing fuel pressure when it's hot. He's ruled out any injector issues. Probably unrelated but one of the codes it gives is for EVAP emissions leak detected but he doesn't think that has anything to do with it. Maybe just a gas cap not being tightened enough at some point.