Abstract: A priming system for small internal combustion engines is operable at engine cranking speeds to prime the carburetor of the engine, and is automatically disabled at engine running speeds. The priming system includes a control valve having an air vane responsive to rotation of the engine flywheel such that, at engine cranking speeds, the air vane positions the control valve to direct pressure pulses from the crankcase breather valve to the fuel bowl of the carburetor for priming and, upon running of the engine, the air vane positions the control valve to divert the pressure pulses from the crankcase breather valve to the throat of the carburetor to recirculate the pressure pulses for combustion with the engine. The priming system also includes a temperature-responsive vent valve which is opened at warm engine temperatures to vent a substantial portion of the pressure pulses to the atmosphere to reduce the amount of priming and prevent flooding of the engine during hot re-starts of the engine.

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 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 scalingly 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.