2003 silverado 2500 hd

[papa dave]

cranks but no start sometimes it starts right up and runs for a few min to a few hours then just stops may start right up or it may take about 30 min have done the passkey reset still have the same problem

[Stealthee]

You need four things to run. Fuel, ignition, compression, and timing. You need to do some diagnosis when it won't start to figure what you don't have.

[maxwedge]

Basics as Stealthee says, I would get a fuel pressure gage on it and look for at least 55 psi, cranking.