I have a 1996 4.3L V6 4x4
It is trying turn over but won't. There is a burning smell under the hood, it isn't oil or fuel.

I have replaced the ignition control module and the ignition coil pack but it will not start.
Batter and alt are good, and it is trying to turn over but will not start.

Any help is greatly appreciated.

 

Check to see if you are getting fuel pressure and also spark.

 

almost sounds like the main ground wire broke or has a bad connections. start there. clean and inspect all the grounds going from the engine, body, and battery. if that doesnt fix it maybe its the main power wire going to the starter is in bad shape.

 

A burning smell is not good. I would locate the source of that before you get too far. That smell could turn into smoke and/or fire...