Abstract: Provided is a general purpose engine having a sufficient cooling function. The general purpose engine 1 comprises: an engine main body 10 having a canister muffler 132 on the side thereof; a cooling mechanism 9 that cools the engine main body 10; and a shroud 4 covering the engine main body 10 and the cooling mechanism 9. The cooling mechanism 9 comprises: a cooling fan 90 that generates cooling air by rotating; and a blowing unit 92 that blows cooling air generated by the rotation of the cooling fan 90, towards the upper section of the engine main body 10. A space S in which the cooling air blown from the blowing unit 92 towards the upper section of the engine main body 10 can flow vertically downwards is formed between the shroud 4 and the canister muffler 132. A return section 40 that guides the cooling air towards a stud bolt 132a that fixes the canister muffler 132 to the engine main body 10 is formed on an inside wall surface of the shroud 4 forming the space S.

Abstract: An improved primary pump for a carburetor is provided. The primary pump has a reduced cost and reduced space construction. The primary pump includes: a flexible cap having a cavity; an inlet open to the cavity of the flexible cap; an inlet side path fluidly coupled to the inlet; an inlet side check valve disposed in the inlet side path; an outlet open to the cavity of the flexible cap; an outlet side path fluidly coupled to the outlet; and an outlet side check valve disposed on the outlet side path, wherein at least one among the inlet side check valve and the outlet side check valve comprises a flap formed in a pump diaphragm of a fuel pump of the carburetor.

Abstract: A manually actuated feed pump is provided with a primer bulb to be manually actuated by an operator. The primer bulb has a pump chamber. A travel-controlled valve connects the pump chamber to a fuel line. The travel-controlled valve has a valve member that is moved by an actuation travel of the primer bulb into an open position that opens the travel-controlled valve. A first spring is operatively connected to the valve member and to the primer bulb. The primer bulb acts through the first spring on the valve member.

Abstract: A carburetor provides a supplemental fuel supply to an engine and includes a body, a fuel metering diaphragm and a fluid pump. The fuel metering diaphragm defines part of a fuel metering chamber and a reference chamber and has at least a portion that is movable relative to the body to increase and decrease the volume of the fuel metering chamber to control fuel flow in the fuel metering chamber. The fluid pump is carried by the carburetor or another component upstream of the carburetor and has an outlet in fluid communication with the metering reference chamber and an actuator arranged to discharge fluid through the outlet to increase the pressure within the metering reference chamber and thereby increase the fuel flow rate from the fuel metering chamber to the air-fuel passage to provide a supplemental fuel supply to the engine.

Abstract: In at least some implementations, a carburetor has a metering system that controls fuel flow from a fuel source to an air-fuel passage. The metering system includes a metering diaphragm sealed to a body of the carburetor to at least partly define a metering chamber between the metering diaphragm and the body, and the metering diaphragm has a continuous layer and a discontinuous layer. The continuous layer is responsive to fluid pressure within the metering chamber and moves against the discontinuous layer to open a metering valve to allow fuel flow from the fuel source and into the metering chamber when said fluid pressure is below a reference pressure.

Abstract: Automobile fuel system pressurization apparatuses include systems that are positionable against or insertable into a filler neck of a fuel tank to provide quicker methods of recharging a fuel pump and a fuel line in an automobile without having to run a starter motor for an extended period. One embodiment of the automobile fuel system pressurization apparatus includes an air pump and an inflatable bladder coupled to the air pump, which is deformable between an expanded state and a deflated state. Another embodiment of the automobile fuel system pressurization apparatus includes an air pump coupled to a filler neck sealing element. The air pump directly provides compressed air to the fuel tank, after compressed air is routed through a centrally positioned thru-hole of the filler neck sealing element. Methods of pressurizing an automobile fuel tank to prime a fuel pump, using automobile fuel system pressurization apparatus are also disclosed.

Abstract: A fuel delivery system for an internal combustion engine. The fuel delivery system includes a diaphragm carburetor for mixing air and fuel, a start preparation system for introducing fuel into the carburetor before a start of the engine, and a fuel enrichment system for providing an enriched fuel and air mixture when the engine is cranked.

Abstract: A hand pump (16) includes a housing (22) having an inlet (18) and an outlet (26) and an actuating body (32) movably mounted in the housing axially and a membrane (46) with a flexible ring section (48) surrounding the stroke axis (34). During stroke movement, the actuating body (32) is pressed with the membrane (46) against the force of an elastic element (42) from a resting position (I) into the pump housing (22) and into an actuating position, and returned to the resting position (I) by the elastic element (72). Thus, the volume of a pump chamber (20) can be modified.

Abstract: Primer apparatus and methods are described herein. An example primer apparatus includes a flexible body defining an internal chamber to be fluidly coupled to a fuel system. The body includes a first layer material having a low permeation characteristic to substantially prevent diurnal emissions from escaping the fuel system, a second layer material adjacent the first layer material having a relatively high resiliency compared to the first layer material to enable the body to return to an uncompressed shape when the body is deflected and released by a user, and a third layer material adjacent to the first layer material such that the first layer material is disposed between the second layer material and the third layer material and having a relatively high resiliency compared to the first layer material to enable the body to return to the uncompressed shape when the body is deflected and released by the user.

Abstract: A fuel delivery system (100) for an internal combustion engine. The fuel delivery system (100) includes a diaphragm carburettor (102) for mixing air and fuel, a start preparation system (104) for introducing fuel into the carburettor before a start of the engine, and a fuel enrichment system (106) for providing an enriched fuel and air mixture when the engine is cranked.

Abstract: A hand operated primer pump for small marine or other engines generally spark ignition engines used on stern drive boats that prevents transfer of hydrocarbons into the atmosphere. The primer generally mimics and replaces prior art rubber primer bulbs in general shape and possibly color, although it can be made in any shape or color. It generally contains a pump that delivers a precise measured amount of fuel with each stroke of the actuator. The primer can have an ergonomically designed actuator that creates the farthest distance from a fulcrum point for maximum leverage and hence, maximum ease of use. The primer is generally designed with a continuous molded fuel path to seal any source of hydrocarbon leakage as well as being made from materials that prevent transfer of hydrocarbons to the atmosphere.

Abstract: A hand operated primer pump for small marine or other engines generally spark ignition engines used on stern drive boats that prevents transfer of hydrocarbons into the atmosphere. The primer generally mimics and replaces prior art rubber primer bulbs in general shape and possibly color, although it can be made in any shape or color. It generally contains a pump that delivers a precise measured amount of fuel with each stroke of the actuator. The primer can have an ergonomically designed actuator that creates the farthest distance from a fulcrum point for maximum leverage and hence, maximum ease of use. The primer is generally designed with a continuous molded fuel path to seal any source of hydrocarbon leakage as well as being made from materials that prevent transfer of hydrocarbons to the atmosphere.

Abstract: Primer apparatus and methods are described herein. An example primer apparatus includes a flexible body defining an internal chamber to be fluidly coupled to a fuel system. The body includes a first layer material having a low permeation characteristic to substantially prevent diurnal emissions from escaping the fuel system, a second layer material adjacent the first layer material having a relatively high resiliency compared to the first layer material to enable the body to return to an uncompressed shape when the body is deflected and released by a user, and a third layer material adjacent to the first layer material such that the first layer material is disposed between the second layer material and the third layer material and having a relatively high resiliency compared to the first layer material to enable the body to return to the uncompressed shape when the body is deflected and released by the user.

Abstract: A handheld primer bulb structure includes an outer layer, an inner layer, an intermediate layer and a chamber. The outer layer is made of a thermoplastic elastic material and has the configuration of a spherical body. The inner layer is made of a fluoroplastic material (fluorocarbon polymer) and disposed on an inner face of the outer layer. The intermediate layer is disposed between the outer layer and the inner layer for affixing the inner layer and the outer layer to each other. The chamber is surrounded and defined by the outer layer and the inner layer and the intermediate layer and has two openings.

Abstract: A hand operated primer pump for small marine or other engines generally spark ignition engines used on stern drive boats that prevents transfer of hydrocarbons into the atmosphere. The primer generally mimics and replaces prior art rubber primer bulbs in general shape and possibly color, although it can be made in any shape or color. It generally contains a pump that delivers a precise measured amount of fuel with each stroke of the actuator. The primer can have an ergonomically designed actuator that creates the farthest distance from a fulcrum point for maximum leverage and hence, maximum ease of use. The primer is generally designed with a continuous molded fuel path to seal any source of hydrocarbon leakage as well as being made from materials that prevent transfer of hydrocarbons to the atmosphere.

Abstract: A hand operated primer pump for small marine or other engines generally spark ignition engines used on stern drive boats that prevents transfer of hydrocarbons into the atmosphere. The primer generally mimics and replaces prior art rubber primer bulbs in general shape and possibly color, although it can be made in any shape or color. It generally contains a pump that delivers a precise measured amount of fuel with each stroke of the actuator. The primer can have an ergonomically designed actuator that creates the farthest distance from a fulcrum point for maximum leverage and hence, maximum ease of use. The primer is generally designed with a continuous molded fuel path to seal any source of hydrocarbon leakage as well as being made from materials that prevent transfer of hydrocarbons to the atmosphere.

Abstract: A hand operated primer pump for small marine or other engines generally spark ignition engines used on stern drive boats that prevents transfer of hydrocarbons into the atmosphere. The primer generally mimics and replaces prior art rubber primer bulbs in general shape and possibly color, although it can be made in any shape or color. It generally contains a pump that delivers a precise measured amount of fuel with each stroke of the actuator. The primer can have an ergonomically designed actuator that creates the farthest distance from a fulcrum point for maximum leverage and hence, maximum ease of use. The primer is generally designed with a continuous molded fuel path to seal any source of hydrocarbon leakage as well as being made from materials that prevent transfer of hydrocarbons to the atmosphere.

Abstract: Carburetor start system comprising a primer pump bulb coupled to a valve-opening mechanism, the primer pump bulb and valve-opening mechanism being operably coupled to a throttle valve and/or a choke valve. Pushing the primer pump bulb causes the throttle valve and/or choke valve to be rotated and releasably fixed in a starting position.

Abstract: The present invention provides an ignition system for a pulse fog generator having a carburetor, a pump for pumping air into the carburetor, and a priming pump for directing a quantity of fuel into the carburetor. The ignition system includes an igniter operable on low voltage, a switch for activating and deactivating the igniter, and a grounding connection for grounding the igniter to the carburetor. The grounding connection for grounding the igniter can include an igniter bracket and a ground wire assembly which couples to the igniter and to a location substantially near a sparkplug of the pulse fog generator.

Abstract: A combustion engine includes a carburetor, which is a fuel supply device for introducing fuel into an intake air of the engine, and a fan housing for enclosing a cooling fan mounted on a front end portion of a crankshaft. The fan housing is formed with a flange so as to extend towards a position proximate to the carburetor, and a manually operable priming pump is fitted to the flange.

Abstract: A fuel system for a carburetor that supports operation of an engine includes a body with a bore, a fuel source communicated with the bore and from which fuel is supplied to the bore for delivery to the engine, a drain unit and a control. The drain unit is communicated with the fuel source to selectively receive fuel from the fuel source and has a fuel chamber and an actuator operable to vary the volume of the fuel chamber. The control is communicated with the actuator to permit fuel flow from the fuel source to the fuel chamber when the engine is shut down and to cause fuel to flow from the fuel chamber to the fuel source prior to starting the engine.

Abstract: A feed pump pumps fuel from a fuel tank. A filter portion includes a filter element for removing foreign matter contained in the fuel discharged from the feed pump. A high-pressure pump pumps the filtered fuel to the internal combustion engine. A return passage is connected with a passage between the filter element and the high-pressure pump for partially returning the filtered fuel to the fuel tank. A priming pump portion has an inlet port, which is connected with the return passage, and an outlet port, which is connected with the filter element. The priming pump portion draws fuel from the fuel tank to supply the fuel to the filter element when being operated.

Abstract: A priming and purging fuel system for an internal combustion engine purges a diaphragm carburetor of the engine of stale liquid fuel and accumulated fuel vapor and air while simultaneously priming the carburetor and/or engine with liquid fuel for starting. A start pump of the fuel system supplies at least liquid fuel to a priming circuit and preferably at least fuel vapor and air to a purging circuit of the fuel system. The priming circuit delivers the priming fuel to the engine via a conduit that leads to an isolation chamber located between an inlet jet and preferably an outlet jet. The cross sectional flow area of the jets are appropriately sized to flow a needed amount of priming fuel to the carburetor and/or engine for starting without flooding the engine. The combination of the enlarged isolation chamber and jets, at least substantially prevents fuel dribble from the priming circuit and into the engine while running.

Abstract: Carburetor start system comprising a primer pump bulb coupled to a valve-opening mechanism, the primer pump bulb and valve-opening mechanism being operably coupled to a throttle valve and/or a choke valve. Pushing the primer pump bulb causes the throttle valve and/or choke valve to be rotated and releasably fixed in a starting position.

Abstract: A manually operable priming pump has a housing formed with an inlet port adapted to be connected to a supply of fuel and an outlet port adapted to be connected to a fuel-delivery system, a body in the housing between the ports and formed with a throughgoing main passage that is completely clear of obstructions. The body is shiftable between an operating position in which the main passage is aligned with the inlet and outlet ports and permits free flow therebetween and a pumping position, and a piston in the body can be manually reciprocated in the pumping position to draw fluid in through the inlet port and expel it from the outlet port.

Abstract: A hand operated primer pump for small marine or other engines generally spark ignition engines used on stern drive boats that prevents transfer of hydrocarbons into the atmosphere. The primer generally mimics and replaces prior art rubber primer bulbs in general shape and possibly color, although it can be made in any shape or color. It generally contains a pump that delivers a precise measured amount of fuel with each stroke of the actuator. The primer can have an ergonomically designed actuator that creates the farthest distance from a fulcrum point for maximum leverage and hence, maximum ease of use. The primer is generally designed with a continuous molded fuel path to seal any source of hydrocarbon leakage as well as being made from materials that prevent transfer of hydrocarbons to the atmosphere.

Abstract: An air intake component and assembly, as well as an associated carburetor assembly and related method of assembly, are disclose. In at least some embodiments, the intake component includes a surface capable of being coupled at least indirectly to a carburetor assembly, where the surface includes first and second orifices, a first channel capable of communicating engine intake air from a first location to the first orifice of the surface, and a second channel by which at least one of the first location and a second location is connected to the second orifice. The second channel is capable of communicating at least one of a primer air pressure pulse from the at least one location to the second orifice and fuel fumes from the second orifice to the at least one location. In at least some further embodiments, the intake component can be fitted with any of several interchangeable covers.

Abstract: A carburetor includes a fuel and air mixing passage with a throttle valve therein, and a bore with a valve therein defining in part a valve actuation chamber and a separate fuel and air mixing chamber in communication with the fuel and air mixing passage at a location downstream of the throttle valve. A fuel passage and an air passage are in communication with the fuel and air mixing chamber. A purge apparatus is in communication with the valve actuation chamber and is operable to move the valve to an open position to open the fuel and air passages to the fuel and air mixing chamber such that a fuel and air mixture may flow from the fuel and air mixing chamber to the fuel and air mixing passage downstream of the throttle valve.

Abstract: A manually operable fuel pump has a housing formed with an inlet port adapted to be connected to a supply of fuel and an outlet port adapted to be connected to a fuel-delivery system, a body in the housing between the ports and formed with a throughgoing main passage that is completely clear of obstructions. The body is shiftable between an operating position in which the main passage is aligned with the inlet and outlet ports and permits free flow therebetween and a pumping position, and pump means connected to the body manually operable for, in the pumping position, drawing fluid in through the inlet port and expelling it from the outlet port.

Abstract: A combustion engine includes a carburetor, which is a fuel supply device for introducing fuel into an intake air of the engine, and a fan housing for enclosing a cooling fan mounted on a front end portion of a crankshaft. The fan housing is formed with a flange so as to extend towards a position proximate to the carburetor, and a manually operable priming pump is fitted to the flange.

Abstract: A priming and purging system and method for an internal combustion engine having a diaphragm carburetor includes a pump in fluid communication with the carburetor, a portion of the engine, and a fuel tank. The pump is manually actuatable to draw liquid fuel and any fuel vapors and gases from the carburetor and to deliver at least some liquid fuel into a portion of the engine to prime the engine and liquid fuel and any fuel vapor and gases toward and preferably into the fuel tank to facilitate purging the carburetor.

Abstract: A carburetor start pump circuit, for starting an engine has an auxiliary fuel pump mounted on a relatively standard carburetor body, a start pulse passage extending through the carburetor body to the auxiliary fuel pump, and a fuel circuit having an intake side which extends from a metering chamber of the carburetor body to the auxiliary fuel pump and a discharge side which is interconnected to the intake side and extends from the auxiliary fuel pump to a throttle bore in the air intake of the carburetor body. To prevent the engine from stalling, a restriction jet is placed within the start pulse passage to prevent the auxiliary fuel pump from discharging fuel into the throttling bore when the engine transmits pulses at high frequencies.

Abstract: A float bowl type carburetor has a fuel and air mixing passage extending therethrough, a float bowl assembly, a priming pump communicated with the float bowl assembly and a fuel supply pipe that is communicates fuel in the float bowl assembly with the fuel and air mixing passage. The priming pump is operable to deliver pressurized fluid into the float bowl assembly in the area of the fuel supply pipe. Preferably, the priming pump discharges fluid in line with the fuel supply pipe so that at least some of the fluid discharged from the priming pump flows directly into the fuel supply pipe to facilitate delivering a rich fuel and air mixture to the engine to facilitate starting the engine.

Abstract: A priming system for the carburetor of a small internal combustion engine which is used with a lawnmower, for example, in which the priming system is remotely actuated. The priming system includes a priming feature for supplying an amount of liquid fuel to the carburetor throat to aid in starting the engine, and an enrichment feature for providing an enriched fuel supply to the engine during a warm-up period. In one embodiment, the priming system includes an automatic primer disabling feature which is operative when the engine is warm to block the supply of priming fuel to the carburetor throat and thereby prevent priming during a warm engine re-start. In another embodiment, the priming system includes a primer reduction feature, which is operative when the engine is warm to provide a reduced amount of priming fuel to the carburetor throat during a warm engine re-start, with respect to the amount of fuel which is supplied during a cold engine start.

Abstract: A method for controlling start of a compression ignition engine having a plurality of cylinders without a cam sensor is provided. Each cylinder includes a respective piston reciprocally movable between respective top and bottom positions along a cylinder longitudinal axis. The method comprises providing a respective fuel delivery assembly for each cylinder. In one embodiment the method further comprises retrieving from memory a set of fuel delivery assembly firing rules and then processing the firing rules so that a firing signal is delivered to each fuel delivery assembly on every crank revolution during a cranking mode of operation. The fuel delivery assembly is arranged to be responsive to any firing signal received during an injection window leading to the top position along the longitudinal axis so as to supply fuel to each cylinder during that injection window.

Abstract: A push button air primer including a priming piston slidably housed in a primer housing and a sealing piston slidably housed in the priming piston. To prime the carburetor, the operator depresses the priming piston causing both priming piston and sealing piston to slide within the primer housing until the sealing piston bears against the carburetor body to seal an opening to an internal vent passage. Further movement of the priming piston forces air from the housing into a fuel bowl, thereby pressurizing the fuel bowl and causing fuel to move from the fuel bowl into the throat of the carburetor.

Abstract: A push button air primer is provided for a carburetor used with a small internal combustion engine. The carburetor includes a primer chamber having a piston sealingly and slidably movable therein, with a return spring biasing the piston outwardly of the carburetor. The piston is depressible by an operator such that, upon initial depression of the piston, a portion of the piston slides past a plurality of vent holes in the wall of the primer chamber to block communication between the primer chamber and an internal vent passage within the carburetor which leads to the carburetor throat and thence to the atmosphere. Thereafter, further depression of the piston reduces the volume of the primer chamber and forces a quantity of air from the primer chamber into the fuel bowl of the carburetor, thereby pressurizing the air space in the carburetor to force a quantity of liquid fuel into the throat of the carburetor to aid in engine starting.

Abstract: A primer assembly is provided including a resilient primer bulb which, along with the carburetor body, defines a variable volume priming chamber. A plunger or blocking element is slidably disposed within the priming chamber. Upon initial depression of the primer bulb, the primer bulb engages and depresses the plunger element toward the carburetor body to seal off an internal vent passage from the primer chamber and the fuel bowl. Thereafter, further depression of the primer bulb forces air from within the primer chamber into the fuel bowl to pressurize the fuel bowl and force an amount of fuel into the throat of the carburetor for priming. Advantageously, the plunger element functions to effectively seal the internal vent passageway from the primer chamber and fuel bowl regardless of the direction from which the primer bulb is depressed.

Abstract: A carburetor start pump circuit, for starting an engine has an auxiliary fuel pump mounted on a relatively standard carburetor body, a start pulse passage extending through the carburetor body to the auxiliary fuel pump, and a fuel circuit having an intake side which extends from a metering chamber of the carburetor body to the auxiliary fuel pump and a discharge side which is interconnected to the intake side and extends from the auxiliary fuel pump to a throttle bore in the air intake of the carburetor body. To prevent the engine from stalling, a restriction jet is placed within the start pulse passage to prevent the auxiliary fuel pump from discharging fuel into the throttling bore when the engine transmits pulses at high frequencies.

Abstract: A carburetor start pump circuit, for starting an engine has an auxiliary fuel pump mounted on a relatively standard carburetor body, a start pulse passage extending through the carburetor body to the auxiliary fuel pump, and a fuel circuit having an intake side which extends from a metering chamber of the carburetor body to the auxiliary fuel pump and a discharge side which is interconnected to the intake side and extends from the auxiliary fuel pump to a throttle bore in the air intake of the carburetor body. To prevent the engine from stalling, a restriction jet is placed within the start pulse passage to prevent the auxiliary fuel pump from discharging fuel into the throttling bore when the engine transmits pulses at high frequencies.

Abstract: A priming system for a carburetor for small internal combustion engines, wherein the priming system is remotely actuated and includes an automatic primer disabling feature operative when the engine is in a warm condition to prevent the supply of an overly rich fuel/air mixture to the engine intake system during warm re-starts, for example.

Abstract: A priming system for a carburetor for small internal combustion engines, wherein the priming system is remotely actuated and includes an automatic primer disabling feature operative when the engine is in a warm condition to prevent the supply of an overly rich fuel/air mixture to the engine intake system during warm re-starts, for example.

Abstract: A carburetor start pump circuit, for starting an engine has an auxiliary fuel pump mounted on a relatively standard carburetor body, a start pulse passage extending through the carburetor body to the auxiliary fuel pump, and a fuel circuit having an intake side which extends from a metering chamber of the carburetor body to the auxiliary fuel pump and a discharge side which is interconnected to the intake side and extends from the auxiliary fuel pump to a throttle bore in the air intake of the carburetor body. To prevent the engine from stalling, a restriction jet is placed within the start pulse passage to prevent the auxiliary fuel pump from discharging fuel into the throttling bore when the engine transmits pulses at high frequencies.

Abstract: A carburetor with a manual priming pump having an integrated fuel drain which provides both the engine manufacturer and end user with an easy way to drain fuel from a fuel chamber of the carburetor. The priming pump has a pump chamber defined by a resilient priming bulb. The pump chamber generally communicates between the fuel chamber and a fuel-and-air mixing passage of the carburetor body and is preferably positioned above the fuel chamber. The dual function of the manual priming pump, prime or drain, is switched by a valve with a rotatable selector member received between a seat and the resilient priming bulb of the pump. The selector member moves between a drain position and a priming position thus enabling draining of the fuel chamber or priming of the carburetor via successive manual depressions of the priming bulb.

Abstract: A priming system for an engine carburetor. The priming system includes a passageway having a first end in fluid flow communication with a variable volume chamber of a primer bulb and a second end in fluid flow communication with a fuel well. The second end of the passageway opens into the fuel well below a static priming fuel level which is in said fuel well and which at least partially extends into said passageway.

Abstract: A carburetor for a small internal combustion engine has a manual priming fuel pump with a resilient valve for allowing fuel flow in a first direction and for preventing fuel flow in a second direction. The resilient valve is reinforced with longitudinally extending ribs to prevent recirculation of fuel through an outlet orifice of the valve in a running engine. The outlet orifice is defined by a distal end of a tubular portion of the valve press fitted and projecting into an outlet passage that communicates with a pump chamber defined by a resilient domed cap. The ribs project laterally outward from the tubular portion within the outlet passage. Integral with an opposite end of the resilient valve is a head which flexes outward to open an inlet passage which then communicates with the pump chamber.

Abstract: A diaphragm type carburetor which has a purge system to remove air and fuel vapor from the carburetor and to fill it with liquid fuel prior to starting an engine fed by the carburetor. The purge system has a primer valve actuated by moving a choke valve of the carburetor to its closed position to inject a small volume of liquid fuel into a throttle bore to provide a richer fuel and air mixture to the engine to facilitate starting it. Desirably, the small volume of liquid fuel is injected into the throttle bore in response to closing of the choke valve without requiring any additional steps such as depressing a button on the carburetor, to do so. Preferably, the choke valve is carried on a shaft which has at least one detent formed therein to provide a camming surface which actuates the primer valve as the choke valve is rotated from its open position to its closed position. Preferably, the choke valve shaft has a pair of detents.

Abstract: An air-fuel mixture generating device includes a main body equipped with a diaphragm-type fuel pump, a fuel injection valve attached to the main body, and a manual fuel pump attached to the main body for filling a fuel passageway with fuel when the diaphragm-type fuel pump is not operating. The manual fuel pump has an inlet port which communicates with the fuel passageway and a pressure-adjusting valve disposed at the inlet port of the manual fuel pump, thereby enabling it to act not only as an intake valve when the manual fuel pump is operated but also as a relief valve for allowing the fuel inside the fuel passageway to escape into a pump chamber of the manual fuel pump when the pressure of fuel inside the fuel passageway exceeds a predetermined pressure.

Abstract: A method of reducing gaseous phase presence in the liquid fuel metering chamber of a diaphragm by providing a “High-Point Pick Up” hole positioned in the optimal metering chamber location (highest) to assure maximum purge evacuation of air and/or other gases prior to engine start-up and during running. This optimal location is dependent upon first determining, in advance of carburetor fuel feed circuitry and/or air purge system design, the orientation of the carburetor as mounted on the engine in its primary operator usage position, or so-called “standard operating position” (SOP). This SOP in turn is determined in the first instance by the engine manufacturer and/or the manufacturer of the portable engine-driven handheld appliance on which the engine is mounted.