Not knowing what you have tried and assuming you don't have the security light flashing...
Check your fuse block and verify it's not blown. Verify you have fuel pressure (50 -60 psi) should which remains constant for a period of time after the power has been removed. If you do not have the pressure its probably the pump. If you have fuel pressure, but is doen't hold, check the fuel pressure regulator.
Was the fuel filter replaced when the fuel pump was replaced?