How does a auto smoke machine work?

Answer 1

A "smoke machine" which is used to detect leaks in the evaporation emissions system works by heating up mineral oil(or baby oil) to the point that if begins to burn and smoke. That smoke is injected into a specific port (shrader valve) in the emissions system. The "smoke machine" only stays on for about 10 minutes then shuts itself off so the oil does not burn unnecessarily.