Method for controlling the fuel supply to an internal combustion engine at start-up and a carburetor

A carburetor for an engine, said carburetor including:

• an intake channel with a venturi section;
• a throttle valve mounted in the intake channel, downstream of the venturi section;
• a choke valve mounted in the intake channel, upstream of the venturi section;
• and
• a fuel supply system that is configured to be set in one of two modes during a start attempt of the engine, the two modes including a lean mode and a rich mode, the rich mode providing more fuel during the start attempt than the lean mode, the fuel supply system including:
• a main fuel path connecting a diaphragm controlled regulating chamber to a main outlet in the region of the venturi section, the main fuel path including an electronically controlled fuel valve,
• an idling fuel path branching off from the main fuel path downstream of the electronically controlled fuel valve and ending in at least one idling outlet in the region of the throttle valve, and
• a start fuel line starting upstream or downstream of the electronically controlled fuel valve and ending in at least one start fuel outlet to the intake channel, wherein the electronically controlled fuel valve, which is located between the regulating chamber and the intake channel, is controlled by an engine control unit that is configured to determine, during the start attempt of the engine, whether to place the electronically controlled fuel valve in an open position to place the fuel supply system in the rich mode or a closed position to place the fuel supply system in the lean mode,
• wherein the engine control unit is configured to use sensor data to determine when to place the electronically controlled fuel valve in the open position or the closed position,
• wherein the sensor data includes data indicative of throttle position, a previous start attempt, engine speed, or engine temperature, and
• wherein if the sensor data indicates the engine is warm, the engine control unit is configured to determine to place the electronically controlled fuel valve in the closed position.

A carburetor for an engine, said carburetor including:

• an intake channel with a venturi section;
• a throttle valve mounted in the intake channel, downstream of the venturi section;
• a choke valve mounted in the intake channel, upstream of the venturi section;
• and
• a fuel supply system that is configured to be set in one of two modes during a start attempt of the engine, the two modes including a lean mode and a rich mode, the rich mode providing more fuel during the start attempt than the lean mode, the fuel supply system including:
• a main fuel path connecting a diaphragm controlled regulating chamber to a main outlet in the region of the venturi section, the main fuel path including an electronically controlled fuel valve,
• an idling fuel path branching off from the main fuel path downstream of the electronically controlled fuel valve and ending in at least one idling outlet in the region of the throttle valve, and
• a start fuel line starting upstream or downstream of the electronically controlled fuel valve and ending in at least one start fuel outlet to the intake channel, wherein the electronically controlled fuel valve, which is located between the regulating chamber and the intake channel, is controlled by an engine control unit that is configured to determine, during the start attempt of the engine, whether to place the electronically controlled fuel valve in an open position to place the fuel supply system in the rich mode or a closed position to place the fuel supply system in the lean mode,
• wherein the engine control unit is configured to use sensor data to determine when to place the electronically controlled fuel valve in the open position or the closed position,
• wherein the sensor data includes data indicative of throttle position, a previous start attempt, engine speed, or engine temperature, and
• wherein if the sensor data indicates the engine is cold and there has been no previous engine ignition, the engine control unit is configured to determine to place the fuel valve in the open position.

A carburetor for an engine, said carburetor including:

• an intake channel with a venturi section;
• a throttle valve mounted in the intake channel, downstream of the venturi section;
• a choke valve mounted in the intake channel, upstream of the venturi section;
• and
• a fuel supply system that is configured to be set in one of two modes during a start attempt of the engine, the two modes including a lean mode and a rich mode, the rich mode providing more fuel during the start attempt than the lean mode, the fuel supply system including:
• a main fuel path connecting a diaphragm controlled regulating chamber to a main outlet in the region of the venturi section, the main fuel path including an electronically controlled fuel valve,
• an idling fuel path branching off from the main fuel path downstream of the electronically controlled fuel valve and ending in at least one idling outlet in the region of the throttle valve, and
• a start fuel line starting upstream or downstream of the electronically controlled fuel valve and ending in at least one start fuel outlet to the intake channel, wherein the electronically controlled fuel valve, which is located between the regulating chamber and the intake channel, is controlled by an engine control unit that is configured to determine, during the start attempt of the engine, whether to place the electronically controlled fuel valve in an open position to place the fuel supply system in the rich mode or a closed position to place the fuel supply system in the lean mode,
• wherein the engine control unit is configured to use sensor data to determine when to place the electronically controlled fuel valve in the open position or the closed position,
• wherein the sensor data includes data indicative of throttle position, a previous start attempt, engine speed, or engine temperature, and
• wherein if the sensor data indicates the engine is cold and there has been previous engine ignition, the engine control unit is configured to determine to place the fuel valve in the closed position.