I have a 2002 Chevy blazer 4x4 that cranks but will not start and when I turn the key off the gauges on dash are working as if the key is still turned on

 

We need to determine if its:

Ignition
Fuel
Mechanical


We usually start with fuel pressure but because you have wonky electrical behavior after you turn it off, lets start with ignition. Do you have spark at the plugs during a crank. If no then check the voltage on the coil and ICM pink wires with key on. Im guessing ignition switch but lets diagnose it properly before loading the parts cannon.

George