Abstract: There is disclosed a new and improved air-fuel metering regulator which provides for extremely fine adjustment of the flow of fuel to the internal combustion engine which may be operating under idling, cruising or various accelerating power circumstances. This is provided, in the preferred embodiment, by the novel arrangement of the separate air and fuel diaphragm and chambers with extremely fine adjustments being provided in both the air or vacuum chamber bodies and the fuel chamber bodies to limit the travel of both diaphragm assemblies in their respective linear directions toward or away from the vacuum or fuel chamber bodies. As a result of the fine adjustments possible and the particular layout of the chambers, more precise and upgraded performance is available in the internal combustion engine as a result of the fuel supply to the internal combustion engine being made more responsive to the various operating conditions of the engine.