Abstract: The operation of an internal combustion engine is regulated by an electronic regulation circuit which utilizes suction pipe pressure to modulate the width of a pulsed signal and to vary the amplitude of a sawtooth wave signal in accordance with the duration of said pulsed signal so that the fuel injection to the engine may be controlled as desired under all operating conditions. The regulation circuitry includes apparatus for modifying the slope of the time versus pressure characteristic of the suction pipe transducer to account for the differences between full load and no load torque of the engine. This is accomplished byvarying the amplitude of the sawtooth waveforms by shunting a portion of the charging current to the sawtooth generator in accordance with the load conditions on the engine.