accelerator pump[ak′sel·ə‚rād·ər ‚pəmp]
A small cylinder and piston controlled by the throttle of an automotive vehicle so as to provide an enriched air-fuel mixture during acceleration.
A pump in a carburetor of a reciprocating engine that provides a rich fuel-air mixture when the throttle is suddenly opened. This permits proper acceleration of the engine. Also called an accelerator pump.