Its called $$$$, they only get so much $$ for diagnosticsI just had exactly the same issue. I took it to the dealer, they kept it overnight, and said they couldn"t reproduce the problem. I told them it was a "losing prime" issue. They said they would keep it overnight again.....I demanded a loaner or rental. After arguing for a few minutes, I got the rental. The next morning they called and said there was nothing wrong. I asked to speak with the manager, I told him that I would take my truck back, but the next time it didn"t start, I was gonna call his cell phone and demand a flatbed towtruck, and another rental.........He decided to "give it another look", and what do you know......they found a small leak at the filter housing. Fixed.no more problems.
Funny how after doing some research on this site, you usually know more about what is wrong with your truck than the guy working on it.....and can often see through their BS.