Crank but no start

May be the injectors or fuel pressure regulator are leaking and bleeding the fuel pressure. Also, craked lines will let in air but not really leak if craked on top. Or it could simply be the relay for the pump doesn't send the signal to the pump to prime it. Listen for the pump when the ignition is switched on and off. If it is priming, see if toggoling the ignition makes it start easier. If so it is loseing it's pressure somewere. When it is a no start it probably builds the pressure for it to start while it's cranking.

Thanks. That sounds familiar because the mechanic said the diagnostic tool flagged low fuel pressure. So it may be what you said about the relay or cracks in the line.