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A small engine carburetor with manually controlled choke and throttle valves and associated idle ports and main metering nozzle supplied with fuel from a common metering chamber. The A/F is automatically adjusted by a solenoid operated poppet valve and/or gear driven needle valve and cooperative ele

A small engine carburetor with manually controlled choke and throttle valves and associated idle ports and main metering nozzle supplied with fuel from a common metering chamber. The A/F is automatically adjusted by a solenoid operated poppet valve and/or gear driven needle valve and cooperative electronic control circuitry and system components built-in to the carburetor. A combined accelerator pump and idle circuit shut-off mechanism is also built-in and mechanically operated by the throttle shaft so that only the main nozzle supplies fuel when the engine is running above fast idle. A mechanical choke/throttle interlock mechanism also prevents partial choking when the engine is running above fast idle, and throttle operation above fast idle when choking. An electric motor worm gear drive unit controlled by the automatic system is detachably coupled to, and provides fine incremental adjustment of, the main metering needle and is self-locking to retain set adjustment during engine running and at engine shut-off. Control system components are arranged in a compact overall package characterized by a laterally offset, skewed orientation of control box and carburetor body, with a diaphragm fuel pump and metering chamber sharing box and body for intercooling of electronic and electrical components by incoming fuel while assisting fuel vaporization in the carburetor venturi passage.

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A manually and semi-automatic electrically controlled carburetor having a heat conductive metal body with a mixing passage extending axially and centrally therethrough and opening at opposed end faces of said body, a manually controlled throttle valve disposed in said mixing passage and movable betw

A manually and semi-automatic electrically controlled carburetor having a heat conductive metal body with a mixing passage extending axially and centrally therethrough and opening at opposed end faces of said body, a manually controlled throttle valve disposed in said mixing passage and movable between closed low idle and an wide open throttle positions, a liquid fuel metering chamber, a main fuel nozzle communicating with said metering chamber and said mixing passage upstream of said throttle valve when in said idle position, a manually controlled choke valve disposed in said mixing passage upstream of said main fuel nozzle and movable between a closed cold start and wide open positions, said body having top and bottom generally flat sides disposed generally parallel with one another on opposite sides of said mixing passage, said fuel metering chamber being disposed at said body bottom side and having a diaphragm and an air chamber cover plate associated therewith, electrically adjustable fuel valve means disposed in said body for controlling flow of fuel from said metering chamber to said main fuel nozzle, a heat conductive metal control box housing mounted on said body over said body top side, said housing having a bottom wall juxtaposed to said body top side and housing side wall means upstanding from said housing bottom wall and defining therewith an interior electronic control component compartment, said compartment containing electronic control circuits and associated electronic components operably adapted to actuate said fuel valve means in response an engine operating parameter sensing signal to thereby automatically adjust the air/fuel ratio (A/F) of an engine operably associated with said carburetor, and engine pressure pulse operated diaphragm fuel pump means including flap valve gasket means mounted between said housing bottom wall and said body top side and associated pump fuel feeding passages and pump diaphragm chamber means disposed in both said housing bottom wall and in said body adjacent said body top side such that pump fuel flow through said pump means to said metering chamber is in heat exchange relationship with said housing component compartment and said mixing passage via said housing bottom wall and said body. Method of adjusting the air/fuel ratio (A/F) of an i.c. engine provided with a carburetor having an electrically adjustable A/F control system and manually controlled mechanical choke and throttle valve control system and associated main nozzle and idle fuel circuits by means of an electronic detector and control unit to which current is supplied by an ignition magnet or generator and which comprises a tachometer, data processing means, an electronic memory, and a control unit for adjusting said ratio, the first derivative of the speed of revolution being used as a parameter for the adjustment, and the adjustment is performed after a period of time during which the speed of the engine has been generally constant, and that generally constant speed is detected by calculating the average value of said derivative, such that the speed of revolution of the engine is considered to be generally constant when said average value is approximately zero and wherein the air/fuel ratio is adjusted stepwise or successively when the engine is operating under load, until said first derivative (speed variations) has reached a predetermined level, or a break point of lean adjustment is detected, said method comprising the steps of: (a) preventing motion of the choke valve from wide open position anywhere when the throttle valve is positioned between approximately fast idle to wide open positions, and (b) shutting off fuel flow to the idle circuit when the throttle valve is positioned beyond fast idle to full open positions. A carburetor having a mixing passage, a throttle valve disposed in said mixing passage and movable between a low idle position and an wide open throttle position, a liquid fuel metering chamber, a main fuel nozzle communicating with said metering chamber and said mixing passage upstream of said throttle valve, at least one idle fuel port communicating with said mixing passage downstream of said throttle valve, means for controlling said carburetor adapted when in operable association with an internal combustion engine to automatically adjust the air/fuel ratio (A/F) thereof to a preferred value, said control means comprising electronic control circuit means and valve means for adjusting the A/F by controlling flow to said main fuel nozzle in response to an actuating signal output of said control circuit means, and idle fuel port shut-off means operably connected to said throttle valve to close fuel supply to said idle port in response to initial movement of said throttle valve from fast idle position toward wide open position and vice versa, and wherein said adjustment valve means comprises a poppet valve actuated by a solenoid to move between an open position allowing total fuel flow to said main fuel nozzle of said carburetor from said metering chamber, and a closed position interrupting said total flow to change the A/F to a leaner mixture for a short period of time.