A throttle body assembly for a combustion engine includes a throttle body having a pressure chamber including a supply of liquid fuel, and a throttle bore with an inlet through which air is received. A throttle valve is carried by the throttle body with a valve head movable relative to the throttle bore. A metering valve is coupled to the throttle body, and has a valve element that is movable between open and closed positions. A boost venturi is located in the throttle bore and has an inner passage that is open at both ends to the throttle bore. The boost venturi has an opening through which fuel flows into the inner passage when the valve element is in the open position, wherein fuel flows from the pressure chamber to the metering valve under the force of gravity or under a pressure of less than 6 psi.

A throttle body assembly for a combustion engine includes a throttle body having a pressure chamber including a supply of liquid fuel, and a throttle bore with an inlet through which air is received. A throttle valve is carried by the throttle body with a valve head movable relative to the throttle bore. A metering valve is coupled to the throttle body, and has a valve element that is movable between open and closed positions. A boost venturi is located in the throttle bore and has an inner passage that is open at both ends to the throttle bore. The boost venturi has an opening through which fuel flows into the inner passage when the valve element is in the open position, wherein fuel flows from the pressure chamber to the metering valve under the force of gravity or under a pressure of less than 6 psi.

A carburettor for supplying gaseous fuels in internal combustion engines, comprises a main body in which there are defined an intake section, a first pressure reduction section, a second pressure reduction section connected to the first section, a supply section connected to the second pressure reduction section, a Venturi device connected to the supply section, wherein the Venturi device forms a central portion of the carburettor, the first pressure reduction section and the supply section extending on opposite sides of the Venturi device, the second supply section being interposed between the first pressure reduction section and the supply section and wherein the supply section further comprises an actuating device that can to allow passage of gas through a third connecting conduit towards the third chamber.

A carburettor for supplying gaseous fuels in internal combustion engines, comprises a main body in which there are defined an intake section, a first pressure reduction section, a second pressure reduction section connected to the first section, a supply section connected to the second pressure reduction section, a Venturi device connected to the supply section, wherein the Venturi device forms a central portion of the carburettor, the first pressure reduction section and the supply section extending on opposite sides of the Venturi device, the second supply section being interposed between the first pressure reduction section and the supply section and wherein the supply section further comprises an actuating device that can to allow passage of gas through a third connecting conduit towards the third chamber.

In at least some implementations, a charge forming device includes a body having a main bore, a fuel metering assembly including a diaphragm that defines at least part of a fuel chamber from which fuel is provided to the main bore and a reference chamber separate from the fuel chamber, a passage communicated with a subatmospheric pressure source and with the reference chamber, and an electrically actuated valve having an open position and a closed position, and wherein the valve at least substantially prevents communication of the pressure source with the reference chamber when the valve is in the closed position and permits communication of the pressure source with the reference chamber when the valve is in the open position to vary the rate of fuel flow from the fuel chamber.

A system and method to improve the efficiency of an internal combustion engine by delivering an air/fuel mixture to the combustion chamber in a pure gaseous state. The system accepts an air/fuel mixture from a carburetor or injector which is placed into a vaporized state before entering an expansion chamber and then the combustion chamber of the engine. An intake track capable of withstanding exhaust gas temperatures of an internal combustion engine is constructed and arranged to cause vaporization of fuel and inhibit the vaporization from condensing.

In at least some implementations, a charge forming device includes multiple throttle bores, an inlet chamber in which fuel is received, at least one fuel passage communicating the inlet chamber with the throttle bores, and a valve having an inlet in communication with the inlet chamber, an outlet and a valve head that is movable and allows flow from the inlet chamber through the outlet when the pressure in the inlet chamber is greater than a threshold pressure.

A system and method to improve the efficiency of an internal combustion engine by delivering an air/fuel mixture to the combustion chamber in a pure gaseous state. The system accepts an air/fuel mixture from a carburetor or injector which is placed into a vaporized state before entering an expansion chamber and then the combustion chamber of the engine. An intake track capable of withstanding exhaust gas temperatures of an internal combustion engine is constructed and arranged to cause vaporization of fuel and inhibit the vaporization from condensing.

A throttle body assembly for a combustion engine includes a throttle body having a pressure chamber including a supply of liquid fuel, and a throttle bore with an inlet through which air is received. A throttle valve is carried by the throttle body with a valve head movable relative to the throttle bore. A metering valve is coupled to the throttle body, and has a valve element that is movable between open and closed positions. A boost venturi is located in the throttle bore and has an inner passage that is open at both ends to the throttle bore. The boost venturi has an opening through which fuel flows into the inner passage when the valve element is in the open position, wherein fuel flows from the pressure chamber to the metering valve under the force of gravity or under a pressure of less than 6 psi.

In at least some implementations, a throttle body assembly for a combustion engine includes a throttle body having a pressure chamber in which a supply of fuel is received and a throttle bore with an inlet through which air is received, a throttle valve carried by the throttle body with a valve head movable relative to the throttle bore to control fluid flow through the throttle bore, and a metering valve carried by the throttle body. The metering valve may have a valve element that is movable between an open position wherein fuel may flow from the pressure chamber into the throttle bore and a closed position where fuel is prevented or substantially prevented from flowing into the throttle bore through the metering valve.