I had the same problem with my 760 ,6 cyl hydro, went as far as taking the pump in to an injection shop-everything was fine. Further searching found that the o-ring from the fuel tank to the transfer pump was cracked letting the fuel bleed back to the tank.Same story you have lots of cranking to get it started, then ran fine for the rest of the day. Try this will only cost you a couple of o-rings. Good luck!!