Abstract: An overflow return tank, especially for receiving return fuel at internal combustion engines with fuel gauge, comprising a receptacle (20, 21, 22) with an inlet (23) located upwardly for a return flow and an outlet (25) and an air bleed hole (24), and with a float (30) located within the receptacle for controlling a valve (26, 36, 31a) located at the outlet of the receptacle. The valve comprises a soft, elastic diaphragm (36), which is connected to the float (30) and upon lifting of the float gradually exposes the outlet (25) by being bent, so that fuel can be taken out from the overflow return tank. Owing to the design of the valve only a small lifting force from the float is required, whereby the fuel amount in the overflow return tank can be maintained substantially constant even at great variations in the return flow. The overflow return tank, besides, can be given small dimensions.