Abstract: A diaphragm valve which may serve as an equal pressure valve or as a pressure equalizing valve of a fuel metering and distributing unit for an externally ignited internal combustion engine. The valve has a flexible diaphragm the diameter of which is clamped between the housing and a bottom plate. Included is an adjusting device for controlling tension of a spring that encompasses the stem of the valve with the lower surface of the spring arranged to rest on the upper surface of the diaphragm. The adjusting device is disposed at an angle relative to the valve axis and engages the rim of a plate that is chamfered to correspond to the inclination of the adjusting member. By means of the adjusting device, the spring plate can be minutely adjusted in its axial position thereby changing the valve spring tension.