Just had new in tank fuel pump installed. the original went bad. No problem starting up in morning but during day after driving, sometimes it will just crank and not start. After several and sometimes many attempts, it will finally turn over. Any help is appreciated...........122,000k miles. Runs great when it runs. THANKS BOB

 

Gonna move this to the Cummins section, you may get more response...

 

Sounds like your injection pump is failing...