Walbro Corporation

Walbro Engine Management, L.l.c.

Gary U Gliniecki

George M Pattullo

Michael P Burns

Paul S Learman

James E VanAllen

Mark S Swanson

Eric G Zbytowski

David L Thomas

Gerald A Hill

Larry D Whittaker

Jeffrey H Krueger

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.

Priming circuit for a fuel system

A carburetor for use with an internal combustion engine has a fuel and air mixing passage, a choke valve with a valve head disposed at least partially in the fuel and air mixing passage and an air bleed passage with at least a portion that is communicated with the choke valve head when the choke valve is in its closed position to at least partially restrict air flow out of the air bleed passage when the choke valve is closed. The air bleed passage preferably provides air to a fuel circuit of the carburetor when the choke valve is open. When the choke valve is closed the air flow through the air bleed passage to the fuel circuit is at least partially restricted to provide a richer fuel and air mixture to the engine during a choke assisted start and warming up of the engine.

Carburetor with an air bleed passage

A carburetor fuel adjustment assembly includes a low speed needle valve and preferably a high speed needle valve threaded into respective receptacles of a carburetor body. Each receptacle defines an elongated cavity which intersects a fuel passage and has a valve orifice or seat. Each needle valve has a shank which threadably engages the respective receptacles and a tip that extends into the axially-aligned orifice or seat. The tip is axially movable relative to the orifice by rotation of the needle valve to control the size of the opening between the valve and orifice for fuel flow. A resilient body cooperates with the valve shank in laterally biasing the tip into a steadfast position relative to the orifice or seat. The lateral bias assures constant area for fuel flow through the orifice by resisting needle movement until a sufficient torque is intentionally applied to the needle valve.

Carburetor fuel adjustment assembly

A carburetor including a main body and a throttle valve received in a mixing passage through the main body. The throttle valve is movable to adjust the quantity of a fuel and air mixture supplied to an engine. A carrier member on the main body has a threaded bore in which a shank of an idle speed adjustment screw is received to adjust and control the idle position of the throttle valve. The idle speed adjustment screw is formed of a polymeric material such that the shank is deformed by engagement with the threaded bore to reliably retain the idle speed adjustment screw in its adjusted position in the threaded bore.

Carburetor with plastic idle speed adjustment screw

A carburetor having a throttle valve co-rotatable with a small diameter throttle shaft having a free end protruding from an exterior side surface of the associated carburetor body. A throttle lever detent arm is co-rotatable on and with the throttle shaft free end adjacent each body surface. Interengageable detents on the detent arm and body surface are spaced radially away from the throttle shaft rotational axis by a distance, for example, of about three times the shaft diameter. The arm and body detents are releasably engageable with one another for thereby yieldably holding the detent arm and hence the throttle shaft and associated throttle valve in any one of a plurality of selected angular settings. Hence, the angular tolerance variation on the set positions of the throttle valve blade as controlled by the detents is now, for example, approximately three times more precise so that the tolerance limits for such positions are now rendered three times tighter than otherwise would be possible when utilizing the prior art. Hence manufacturing tolerances do not need to be tightened up in order to achieve the exemplary three-fold improvement in operational tolerances of the carburetor throttle control detent mechanism. The invention thus provides a low cost throttle control detent mechanism that enables fine increment, positive stops at predetermined valve blade settings, such as the W.O.T. (wide-open throttle), idle and closed valve positions.

Carburetor throttle control detent mechanism

A fuel needle valve assembly of a carburetor has a retainer which yieldingly restrains the rotational fuel flow setting capability of the needle valve. The retainer engages a shank of the needle valve and a parallel shaft, both of which project from the carburetor body. The retainer exerts a force which laterally displaces the projecting shank with respect to the shaft. The retainer has sufficient strength to ensure the factory set rotational setting of the fuel needle valve does not alter when a limiter cap is press fitted to a distal head of the needle. Furthermore, wherein the shaft is also a shank of a second needle valve, the same retainer laterally displaces the projecting shanks of both needle valves.

Carburetor valve rotational setting retainer assembly

An electric fuel pump module includes a fuel pump driven by an electric motor. The motor has an armature provided with a commutator having a flat face. Brushes engage the flat face of the commutator to supply current to the armature. A groove in the flat face of the commutator provides relief preventing fuel from becoming trapped between the brush and the commutator face. The groove extends in a circular loop around the axis of rotation of the armature and may be centered on or laterally offset from the axis of rotation.

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Ruth, MI, United States of America

Gary U Gliniecki