My 2004 jeep Cherokee Laredo won't start?

This Laredo has a 6 Cly. And in the morning when the motor is cold it turns over but want start, I can then turn the key off & count to 30, then turn the key to start & it starts right up.
And if the motor is hot are should I say after I have ran the Eng. & turn it off & I sat for around 45 min. It will then still start right up with no problem.
I can't hear the fuel pump at any time when it's cold are hot.
I have been told its the fuel pump but it seems like if that was it wouldn't do this all the time.
Is there a valve are a switch somewhere that keeps the fuel from running back into the tank that has gotten weak & is slowly leaking fuel back to the tank ( looses its prime )are does anyone know if this is built into the fuel pump.