Help with no restart please

[Sclan5]

Hello had a question on my 7.3 wrecker. It has been running good for quite sometime so I cant complain but here is my problem and hopefully you all can help me. Oil gauge has been reading 1/4 way up lately and under acceleration drops off to zero. I dont believe to be a true oil pressure problem as this truck has been like this for 2 months now. The problem My driver encountered today is this.... when you shut it off imeidiatley after shut off if you try to restart it will crank and crank with no restart. Once it cools it will start. I am quite familiar with the powerstroke and have spent many hours working on them as a diesle mechanic. I am quite familiure with the cam sensor problem. This is not that though. I have never since owning the truck 4 yrs been able to access the pcm via snap on scanner. It will not communicate so code retrieval has been impossible that way. Can someone please lead me in the right direction. Your help is greatly appriciated.

Thanks Chris