The invention relates to a control device for the adjustment of the injection timing and/or the pumping rate of a fuel injection pump for IC engines in which the control commands from a microprocessor are transmitted by way of an electrical stepper motor via motion transmitting members with an intermediate spring force storage means to a control rod of the pump, there is a return compression spring with which the control rod may be returned from any position thereof to the zero delivery position. The stepper motor, the motion transmitting members, the spring force storage means and the return spring, an electro-mechanical tachometer generator driven by the injection pump shaft and responding to the speed of rotation thereof and a step generator responding to the steps of the stepper motor, are arranged as a sub-assembly, which is either adapted to be mounted on the outside of the injection pump in an assembled condition or, with the essential components in an assembled condition, are able to be connected with other assembled parts on the control rod and/or on the injection pump shaft when the injection pump is fitted in place.