I have a 85 chevy 10 series that wont start. The truck was running fine and one day I jumped in, turned the key and nothing happened. I've replaced the ignition switch, battery, and starter. When I test the starter it spins but the engine does nothing. What next?

 

sounds like the starter is not kicking out. Try tapping the starter while trying to start it to see if it frees up.

 

Well brother three things will make an engine run or not run. Fuel, Air, or Spark. Could usea little further info on your ride, engine size, Carbureted or not. Quick way to test if the engine is getting spark, Pull the coil wire out of the distributor and hold it close to a ground source, The frame or the side of the block. Frame is best, Hold the coil wire end close to the frame I would say about a half inch away, You will want to have someone crank over the engine a little bit and see if the coil wire produces spark. You need to check to see if the engine is getting fuel as well if that does not cure your woes. I am assuming the engine is turning over. If the starter is not turning over while it is installed you may have a bad starter relay. These are all just thoughts as you gave limited info.

 

You need to get a test light and follow the voltage...could be a burnt fusible link,or a faulty neutral switch maybe