In fuel feeding piston pumps, there is a danger that the shaft bearing be affected by fuel entering the area of the shaft bearing. In the disclosed fuel pump (2), a separating space (20) is provided between the shaft bearing (14) and a fuel-containing chamber (16). The separating space (20) contains air, for example, as separating medium, and communicates with an air inlet of the internal combustion engine. This ensures that no fuel can escape into the area of the shaft bearing (14) nor outwards. This fuel pump is particularly suitable for internal combustion engines in which the fuel must be supplied under high pressure.