Walbro Corporation

Anthony M Kueffner

William E Galka

Ronald H Roche

Peter P Kuperus

Dale P Kus

Kevin L Williams

Paul S Learman

Joseph M Graham

Timothy K Grifka

Bradley D Hilbig

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.

Carburetor fuel pump

A fuel injection system for a two-stroke small engine has a charge forming device with an injector mixing passage which forms a rich fuel and air mixture supplied to a tuned injector tube connected adjacent one end through a port to the engine cylinder and adjacent the other end to the engine crankcase. The charge forming device has a high speed fuel circuit which supplies at least a majority of the fuel to the mixing passage under wide open throttle operating conditions and preferably a minor portion of the fuel is also supplied by an idle fuel circuit which under engine idle conditions preferably supplies essentially all of the fuel to the engine. A separate inlet air flow passage of the charge forming device also supplies primarily air to the crankcase of the engine for transfer to the cylinder. Under engine wide open throttle conditions, preferably a very minor quantity of fuel with oil therein is supplied through the inlet air flow passage to the crankcase and transferred to the cylinder to provide lubrication of the moving parts in the crankcase and some cooling of the engine.

Small engine fuel injection system

An engine fuel apparatus has a fuel and air mixing passage through which a rich fuel and air mixture is provided to an engine to support the operation of the engine at idle and low speed, low load engine operation, and a pressurized fuel delivery passage provides liquid fuel to a downstream fuel injector for operation of the engine at high load, high speed and wide open throttle engine operating conditions. A shut-off valve prevents the flow of fuel to the mixing passage when a throttle valve therein, which controls engine operation, is opened a predetermined amount from idle to prevent the flow of the fuel into the mixing passage at high load and/or high speed engine operation. Another shut-off valve prevents the flow of pressurized fuel to the downstream fuel injector device when the throttle valve is between idle and a predetermined position off of idle to prevent the flow of pressurized fuel to the fuel injector device under low speed, low load engine operation. Desirably, a camshaft rotated in response to rotation of the throttle valve is used to actuate both shut-off valves.

Engine dual fuel supply apparatus

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Caro, MI, United States of America

Anthony M Kueffner