My first thought is to have a fuel pressure test gauge hooked up to see what is happening with your fuel pressures.

You should get good fuel pressure in the prime mode just by turning key on without starting engine. Possibly it is takes 3 prime modes before you get enough pressure to start the engine.
If so, look for defective pump, filter/regulator.

If you don't have access to a test gauge, one of the auto parts stores may lend you one. Very easy hook up.

James