The fuel injection pump has a piston (12) acting in a cylindrical boring (10) of a cylindrical bush (11). In the cylindrical boring (10), a pump working chamber (40) is limited by the piston (12) on one side and an electrically controlled valve (32) on the other. The pump working chamber (40) can be connected on the intake stroke of the piston (12) with an intake chamber (18) via the valve (32) to control the injection piston stroke. The cylindrical bush (11) is partly surrounded by an annular space (41) through which the fuel flows between the pump working chamber (40) and the inner chamber (18). From the annular space (41) branches a by-pass (43) through which the fuel flows into a further annular chamber (48) partly surrounding the valve (32). The annular chamber (48) is relieved towards the fuel tank via a return line. The two annular chambers (41, 48) have fuel flowing continuously through them owing to the pressure prevailing in the inner chamber (18), thus providing cooling for the pump working chamber (40) and the valve (32).