My truck runs for about 30 seconds then dies and will not restart

Question

Truck runs for about 30 seconds then dies when I turn my key over my relays click (there is one relay that after I release the ignition switch clicked again I have replaced many of the relays  battery new alternator good fuse able link intact recently replace the egr valve new coils as well  one last note ( when it starts and runs I check to see if I have pressure in the fuel rail I don't hope I can get some good info no money's to take it to the shop already paying for a new transmission

Answer 1

This is fuel pressure or the fuel pump,listen to the fuel pump as the key is cycled it's usually smooth , if it's rough sounding you need a fuel pump,