A fuel injection pump for a diesel engine includes an input shaft rotated with the crankshaft, and a housing and a plunger which slides in a bore formed in the housing and is coaxial with the input shaft, with a high pressure chamber being defined at an end of the plunger between it and the bore. The plunger rotates with the input shaft and reciprocates so as to pump fuel at high pressure from the high pressure chamber to the engine cylinders, under the control of an electrically actuated electromagnetic valve, comprising a solenoid coil, which selectively vents the high pressure chamber according to the control of a control means, so as to provide fuel injection in appropriate amount to the diesel engine. There is provided a means for determining whether or not the voltage across the solenoid coil of the electromagnetic valve, when supply of power thereto changes from the ON to the OFF condition, rises higher than a certain value, or not. If a determining means detects that this voltage across the solenoid coil has not so risen, this lack of high transient voltage spike indicating that the solenoid coil may be discontinuous or functioning abnormally, then the engine is restrained. This restraint may consist of interrupting fuel flow to the engine to totally stop it, or of restricting air intake to the engine so as to put a ceiling on its rotational speed.