Fuel feed system for an internal combustion engine

In a fuel feed system for an internal combustion engine, of the type comprising:

• a fuel tank,
• an injection pump,
• a fuel feed duct leading from said fuel tank to said injection pump for feeding fuel to said internal combustion engine,
• a fuel feed pump in said fuel feed duct for feeding fuel from said fuel tank to said injection pump,
• at least one fuel filter in said fuel feed duct upstream of said injection pump, and
• a return duct leading back to said fuel tank for excess fuel fed by said fuel feed pump to said injection pump,
• the improvement wherein
• said fuel filter is provided with an electrical resistance,
• a first electrical switch,
• a first temperature sensor positioned to sense the temperature of the fuel in said fuel feed duct at a point upstream of said filter,
• said electrical resistance operating, when energised, to heat by the Joule effect fuel passing through said filter, and being connectable to an electrical source by means of said first electrical switch the closing and opening of which is controlled by said first temperature sensor in such a way that said first electrical switch is closed when the temperature of the fuel at said point upstream of said filter is lower than a first threshold value,
• a solenoid valve having an inlet in said return duct downstream of said injection pump, and two outlets,
• first and second branch ducts connected to said outlets, said first branch duct leading in to said fuel tank, an end portion of said first branch duct being of sinuous form within said fuel tank and said second branch duct joining said first branch duct upstream of said tank
• said solenoid valve operating selectively to direct fuel flowing in said return duct into one or other of said first and second branch ducts connected to said two outlets thereof,
• a heater in said first branch duct,
• a second electrical switch,
• a second temperature sensor positioned to sense the temperature of the fuel in the fuel tank, said solenoid valve being electrically connectable to the electrical source by means of said second electrical switch the closing and opening of which is controlled by said second temperature sensor in such a way that fuel is directed by said solenoid valve into said first branch duct when the second sensor senses that the temperature of the fuel in said tank is lower than a second threshold value, which is higher than said first threshold value.