components via signal and control lines 37 the signal and control lines 37 are only slightly indicated for the sake of clarity the fuel fractionation device shown in fig1 operates as follows at the beginning of a cold start of the internal combustion engine for example as a result of a starter motor being actuated the gas pump 14 is activated and the valve 9 is opened while the valve 33 is closed this position of the valves leads to a reduced pressure being generated in the fuel vessel 1 via the suction line 13 and this reduced pressure spreads to the carrier gas feed 7 so that air can be sucked out of the environment 11 through the activated carbon filter 10 in the gas distributor 4 this air passes through its outlet openings 6 distributed as finely as possible into the fuel 2 where it rises through the fuel 2 and is preferentially enriched with low boiling fuel components before collecting in the gas collection space 12 of the vessel 1 on account of the gas being sucked out through the suction line 13 the air fuel fraction mixture formed in this way is sucked out of the gas collection space 12 by the gas pump 14 and is fed to the separator 16 via the pressure line 17 in the heat exchanger 18 the compressed air fuel fraction mixture is cooled with the result that the fuel fraction is liquefied according to a particular embodiment the fuel 2 of the fuel tank 1 can be used as cooling medium whereby the fuel is heated which enhances the fractionation of the fuel 2 the heat exchanger 18.