Why would a 1991 ford mustang turn over but not start?

Answer 1

You need electricity, air and fuel for an engine to run (start). Electricity is the spark, just because it cranks doesn't mean it will run. Remove a plug wire and place it close to a metal portion on the engine (not Aluminum). Have someone else crank while you observe. If you see spark, move on to fuel/air. Check to ensure you are getting fuel by checking the injectors, or noticing the smell of gasoline while you are cranking. If the smell becomes more noticable, they probably work. Not the best way to check them, but you would be getting some fuel. Air is delivered via the valves. Your valves are opened/closed by the timing belt or chain. This also controls the "timing" of the spark. Without the belt or chain, the car will not start.