Question 580, Aircraft General Knowledge - Airframe, Systems, Powerplant - ATPL - Airline Transport Pilot license

Heat produces vapour plugs in the fuel line.
Burnt gas plugs forming and remaining in the exhaust manifold following an overheat and thereby disturbing the exhaust.
Abrupt and abnormal enrichment of the fuel/air mixture following an inappropriate use of carburettor heat.
Water Vapour Plugs Are Formed In The Intake Fuel Line Following The Condensation Of Water In Fuel Tanks Which Have Not Been Drained For Sometime.