PURPOSE: To improve engine startability by providing a chamber in which fuel in a metering chamber is temporarily drawn and stored in the metering chamber of a diaphragm type carburetor, and drawing the said fuel to store there during engine stoppage, and then returning it to the metering chamber when restarting the engine.

CONSTITUTION: A manual pump 39 for storing fuel communicates with the metering chamber 2 of a diaphragm type carburetor 1 through tubes 37, 38. The lug 40 of the manual pump 39 is drawn during engine stoppage to draw and store the fuel in the metering chamber 27. Therefore, the fuel in the metering chamber 27 which is evaporated by remaining heat during the engine stoppage can be prevented from spouting out through nozzles 22, 24. When restarting the engine, the fuel in the manual pump 39 is again introduced into the metering chamber 27 by pushing the lug 40 in, resulting in prompt engine starting.