If your fuel pump has never been replaced on your 2000 model year truck, it can most certainly be bad. General Motors trucks are notorious for fuel pump issues. You must have between 55 and 62 psi fuel pressure to start your truck...any less and it wont start. You can try switching the fuel pump relay with another relay of the same type in your relay box, but in order to properly diagnose the system you will need to have a fuel pressure gauge. The fuel pump can actually be running but not building enough pressure, however without a gauge it will be impossible to diagnose.