Joejo

My truck is a 2009 F150 4.6 l. The truck was running fine when I parked it. It was parked for a few days. The next time I went to drive it; it wouldn't start. It just cranked over, but it wouldn't start. I checked to see if the fuel pump was coming on, and I could hear it come on. My next step was to check the fuel pressure. Before attaching the pressure gauge, I bled the residual fuel pressure from the fuel rail. Then I cranked the engine over to see if it would start, and it did start. I turned the engine off bled the fuel rail and attached the pressure gauge. After starting the engine again, the gauge read at 50 psi. I then turned it off and waited 30 minutes to see if the pressure was dropping rapidly. The pressure dropped slowly reaching 0 after 24 hours. I think it might be my pressure regulator. Is 50 psi too high? Would that cause my engine not to start? What do you think is going on?