A throttle body fuel injection system and method that is arranged to easily replace four-barrel carburetors includes a throttle body assembly with four main bores, each with a throttle plate and an associated fuel injector. Each injector feeds fuel into a circular fuel distribution ring via a fuel injection conduit, which introduces pressurized fuel into the air stream. The fuel distribution rings and bores have profiles that avoid constrictions for to prevent low pressure zones according to the Venturi effect. The throttle body includes an idle air control circuit having a port opening into main intake bores downstream of the point of fuel distribution into the air stream, thereby reducing the tendency for a lean fuel mixture at idle. An ECU “feed forward” algorithm controls fuel injection as a function of the position of the idle air control valve.

A throttle body fuel injection system and method that is arranged to easily replace four-barrel carburetors includes a throttle body assembly with four main bores, each with a throttle plate and an associated fuel injector. Each injector feeds fuel into a circular fuel distribution ring via a fuel injection conduit, which introduces pressurized fuel into the air stream. The fuel distribution rings and bores have profiles that avoid constrictions for to prevent low pressure zones according to the Venturi effect. The throttle body includes an idle air control circuit having a port opening into main intake bores downstream of the point of fuel distribution into the air stream, thereby reducing the tendency for a lean fuel mixture at idle. An ECU “feed forward” algorithm controls fuel injection as a function of the position of the idle air control valve.

A fuel supply system for small two-stroke internal combustion engines for e.g. chain saws, line trimmers and similar hand-held power-tools including a diaphragm carburetor (20) equipped with a purging system (80a, 81a) or priming system (80b, 81b) for facilitating starting of the engine (1). Downstream of the diaphragm (30), the carburetor has a fuel valve (60) with a fuel cavity (73), which when the valve is not closed being connected via a fuel conduit (37) to a fuel nozzle (35, 36) in a main air passage (21) in the carburetor. The purging system or priming system including a fuel line (80a; 80b), which is provided with a manually operated pump (81a; 81b) and is connected between a fuel tank (26) and either the fuel cavity (73) or the fuel conduit (37).

An attachment for purging the inside of the carburetors which is comprised by a tubular device having a carburetor connecting member and quick connect receiver extension. The attachment is connected through the bottom of the carburetor or through the feed fuel line of the carburetor. The attachment is attachable to a quick disconnect fitting which can be connected to a conventional car tire air nozzle or pressurized can with the same fitting as the car tire nozzle. The attachment allows all the jets and passages located on the inside of carburetor to be purged at the same time with multiple short blasts of compressed air or pressurized can solvent but without the carburetor being removed from the engine or taken a part. The same principles can easily be applied to all type carburetors for either a two or four-stroke engine.

In at least some implementations, a carburetor includes a body, a fuel pump diaphragm and a pressure pulse passage. The fuel pump diaphragm is carried by the body and defines in part a fuel chamber on one side of the fuel pump diaphragm and a pressure pulse chamber on the other side of the fuel pump diaphragm. The pressure pulse passage communicates the pressure pulse chamber with a pressure pulse source to provide pressure pulses in the pressure pulse chamber to actuate the fuel pump diaphragm. The pressure pulse passage includes an inlet communicating with a passage in which pressure pulses are present and the inlet is spaced from a surface defining the passage in which pressure pulses are present.

A control diaphragm for controlling a fuel feed in a diaphragm carburetor of an internal combustion engine, includes a central, substantially flat feeling region, a functional region circumferentially extending around the feeling region in a concentric manner, and a peripheral fastening border for fastening the control diaphragm. The control diaphragm closes off a control chamber of the diaphragm carburetor in a sealing manner in the installed state and is operatively connected by the central feeling region to a controlling lever of the diaphragm carburetor arranged in the control chamber, which controlling lever feels the axial deflection of the feeling region in accordance with an operating-related pressure change in the control chamber. The control diaphragm is composed of a temperature- and fuel-resistant, non-elastomeric and uniformly thick plastic film, in which a plurality of concentric corrugations forming the functional region are formed so that axial deflection of the feeling region progresses in dependence on the operating-related pressure change in the control chamber in accordance with a predefined displacement/pressure characteristic curve.

A throttle body fuel injection system and method that is arranged to easily replace four-barrel carburetors includes a throttle body assembly with four main bores, each with a throttle plate and an associated fuel injector. Each injector feeds fuel into a circular fuel distribution ring via a fuel injection conduit, which introduces pressurized fuel into the air stream. The fuel distribution rings and bores have profiles that avoid constrictions for to prevent low pressure zones according to the Venturi effect. Fuel is injected through downward-facing outlets at or near the bottom end of the rings. The fuel injection rings are two-piece, each formed of an insert pressed into an outer housing. The insert includes axial grooves intervaled about its exterior circumference of insert that are joined by a circumferential groove formed about the insert. The grooves are in fluid communication with a conduit that supplies fuel from a fuel injector.

A throttle body fuel injection system and method that is arranged to easily replace four-barrel carburetors includes a throttle body assembly with four main bores, each with a throttle plate and an associated fuel injector. Each injector feeds fuel into a circular fuel distribution ring via a fuel injection conduit, which introduces pressurized fuel into the air stream. The fuel distribution rings and bores have profiles that avoid constrictions for to prevent low pressure zones according to the Venturi effect. Fuel is injected through downward-facing outlets at or near the bottom end of the rings. The fuel injection rings are two-piece, each formed of an insert pressed into an outer housing. The insert includes axial grooves intervaled about its exterior circumference of insert that are joined by a circumferential groove formed about the insert. The grooves are in fluid communication with a conduit that supplies fuel from a fuel injector.

A carburetor with a fuel and air mixing passage and a fuel delivery system may include a valve actuated by a diaphragm with no penetrations through at least the portion of the diaphragm exposed to a fuel metering chamber. The diaphragm may include at least two convolutions increasing a surface area of the portion of the diaphragm exposed to the fuel metering chamber relative to the surface area of a plane exposed to and covering the fuel metering chamber. A diaphragm may be in the form of a bellows with at least two convolutions. The diaphragm may be made of a suitable polymer or one or more pieces of a thin metal sheet or foil.

A carburetor may include a body having a main bore from which a fuel and air mixture is discharged for use by an engine, a throttle valve head, a choke valve head and a flow directing feature. The throttle valve head may be carried by the body and is moveable between an idle position and a wide open position to control at least some fluid flow through the main bore. The choke valve head may also be carried by the body and is moveable between a first position and a second position to at least in part control fluid flow through the main bore. And the flow directing feature associated with the choke valve head or the throttle valve head may alter at least one of the velocity or direction of at least a portion of the fluid that flows in the main bore.