Fuel injection pump

A fuel injection pump for internal combustion engines comprising a fuel supply chamber arranged to supply fuel provided by a fuel feed pump to a pump work chamber, said pump work chamber being defined by a pump piston disposed within a cylinder bore of the fuel injection pump, said feed pump communicating via an intake line with a fuel supply tank from which said fuel is drawn, the pressure in said fuel supply chamber being controllable in accordance with at least one operating parameter of the internal combustion engine via at least one valve means, said at least one valve means being controlled by signal means indicating occurrence of a special operating state of the engine to vary fuel supply to the pump work chamber from the fuel supply chamber, said signal means including an electric control unit arranged to control a fuel injection quantity regulating member associated with said pump piston for determining a fuel injection quantity deliverable by each supply stroke of said pump piston, said at least one valve means being disposed in a bypass line arranged to circumvent an overflow throttle adapted to relieve said fuel supply chamber, said at least one valve means being controllable to assume selectively variable valve positions for a duration of said special operating state, one of said variable valve positions being an opening position in which a fuel pressure drop is effected in the fuel supply chamber, whereby control over said fuel injection quantity is provided in an engine emergency during normal injection control failure.