Patent ID: 7028993

Claim:
A charge forming apparatus for a combustion engine comprising: a body; a fuel-and-air mixing passage defined by the body, the mixing passage having a venturi region disposed between an air inlet region and a mixture outlet region, wherein air flows from a near atmospheric air source through the air inlet region and into the engine from the mixture outlet region; a throttling choke valve disposed in the air inlet region of the mixing passage, the throttling choke valve having a closed position for starting of the engine, an idle position and a full open position; a flexible diaphragm having a first surface, an opposite second surface, and a peripheral edge; a fuel metering chamber defined between the body and the first surface; a fuel feed passage communicating between the fuel metering chamber and the venturi region of the mixing passage, wherein liquid fuel flows into the venturi region for mixing with air flowing from the air inlet region; a cover; a reference chamber defined between the second surface and the cover, wherein the peripheral edge is engaged sealably between the cover and the body; a reference passage communicating between the reference chamber and the air inlet region downstream of the throttling choke valve when in the idle position; an air bypass channel communicating between the near atmospheric air source and the mixing passage downstream of the choke valve; and wherein the air bypass channel is dry and communicates directly with the mixture outlet region of the mixing passage and wherein the charge forming apparatus does not have a fuel idle circuit at the outlet region.