To prevent overheating of an engine by converting an accelerator opening signal used for calculating a fuel-injection rate into a dummy accelera tor opening signal of a predetermined pattern programmed beforehand when an engine high temperature condition is detected, and inputting the signal to an electronic control type fuel injection device.

During operation of an engine 2, it is judged in an ECU 71 whether an engine is in a high temperature condition from a water temperature detected by a water temperature sensor 75. In the engine high temperature condition, it is judged whether a real accelerator opening is zero or not from an output of an accelerator opening sensor 73. In the case where the accelerator opening is not zero, a counter is operated, a present accelerator opening is held until a constant time is lapsed, and present engine rotating speed is held. After a time is lapsed for one hour, an accelerator opening is converted into a dummy accelerator opening (0) memorized in a ROM, and engine rotating speed is reduced to an idling condition so as to prevent an overheating condition of the engine.