1998 chevy k 2500 cranks but wont start , - Silverado 2500HD Chevrolet Cars & Trucks

See if you're missing fuel or spark.
Does the fuel pump buzz for about 2 seconds when the key is first turned to ON? Do you have about 60psi of fuel pressure? Are your fuses good?
Then you can probe injector wires and have the ignition module tested at an Auto Zone.

Pull a coil wire, do you get spark? Do you have power to the coil? Again, test the ignition module.