For the past 3 or so years my truck has had a bad habit of sporadically refusing to restart after going after shutting off the engine. It would sputter as if was on 2 cylinders but not fully catch ( like not getting enough gas). Usually after a few hours wait it would start normally. Then it would run for several weeks normally, but I new there was a good chance I would have the same problem. A couple of days ago it just turned over with no indication it would ever start. I have had it towed to my local mechanic a couple of times . By the time they got to it, it always started and they could not re-create the problem. Does this sound like a fuel pump or relay? They didn't want to replace the fuel pump since they were not sure that was the problem.

 

The shop is being honest.
Test until something shows is the only way unless you get lucky.
When it fails, first thing is to test fuel pressure, then you either rule that out or found the source of the no start. Why would you spend several hundred dollars on dropping the tank and a pump then still have the same issue?
It could even be the harness to the coils or even the crank sensor.
Any of these will not let the motor start.
Could even be a fuse or the PCM relay seating.
Good luck.