Fuel system for internal combustion engines

In the fuel system of an internal combustion engine including a fuel pump for supplying fuel to a carburetor through a fuel line, the improvement comprising,

• heater means for heating said fuel line at a position intermediate said fuel pump and carburetor,
• said fuel line including an air orifice at a position upstream of said heater means,
• means for adjusting air flow through said orifice,
• a bypass fuel line having one end in communication with said fuel line upstream of said air orifice and an opposite end in communication with said carburetor for supplying fuel thereto, and
• a thermally controlled valve interposed along said bypass fuel line, said thermally controlled valve being in thermal communication with said heater means so as to close when the temperature of said heater means is above a predetermined temperature and to open when the temperature of said heater means is below said predetermined temperature,
• said valve including an orifice therethrough which is adapted to provide limited fuel flow through said valve in both the closed and open positions therefor.