Abstract: A mechanism for idling position adjustment of a diaphragm carburetor will be described. The carburetor includes an idling nozzle which receives a fuel/air emulsion from an emulsifying chamber under idling conditions. The emulsifying chamber receives fuel from a fuel chamber and air from an acceleration port opening into the mixing passage. Furthermore, the emulsifying chamber communicates via a flow control valve to a venting port opening into the mixing passage. The flow control valve is coupled to the shaft of the throttle valve via mechanical connection means so that the idle position of the throttle valve is varied in accordance with manual adjustments of the flow control valve. This allows to adjust the fuel/air ratios under idling conditions by means of a single adjustment member.