A fuel state control unit for use with internal combustion engines can include a primary heating chamber, a secondary heating chamber, and an expansion chamber. The primary heating chamber has a fuel conduit through which fuel is conveyed. A heater in the primary heating chamber transmits heat to the conveyed fuel in the primary heating chamber. The heater is controlled to maintain a predetermined temperature of the fuel. The heated fuel from the conduit is conveyed into a secondary heating chamber. A pressure plate separates the secondary heating chamber from the expansion chamber. The ports of the pressure plate can regulate the flow of the fuel into the expansion chamber. The heated fuel in the expansion chamber can then be conveyed to an engine so as to increase engine efficiency and reduce the amount of pollutant gases in the engine exhaust.