Abstract: It is known that enriching fuel with oxygen improves combustion and thus reduces fuel consumption, improves performance and reduces pollutant and soot particle emission. In order to prevent the air admixed into the fuel before the air is introduced into the combustion chamber from forming air bubbles in the supply pipe, the fuel-air mixture is selectively degassed depending on the size of the air bubbles. The fuel is fed by a feed pump (4), through a suction pipe (2), from a tank (1) into an apparatus (3), and from there into an internal combustion engine (5). Air is admixed by device (6). The apparatus (3) contains a degassing chamber (7) with a floater (8) that closes the lower admission (10) with a sealing cone (9) and that controls with an actuating pin (11) an inlet valve (12) depending on the level of fuel in the chamber.