My 1991 corvette won’t start. How do I know whether this is a VATS issue or something else?

 

Welcome to the forums, check the fuses (all of them, ign, fuel pump, ecm) first to make sure you don't have a bad one, if you haven't already. Pull a spark plug wire and check for spark. Check the fuel system to see if you can hear the fuel pump when the key is turned on, and has fuel pressure, and for injectors use a 12v test light and see if the injectors are getting power. Doing this while turning the engine over. That should get you going in the right direction..