Anti-flood circuit for use with an electronic fuel injection system

Abstract

A pulse width computer for a fuel-injected internal combustion engine generates injector actuation control pulses, the widths of which increase with decreasing engine temperature. These actuation control pulses are normally applied to control an injector drive circuit that, in turn, controls the duration of activation of one or more electromagnetically-actuated injectors in synchronization with the engine cycle. During engine cranking operations, the widths of the injector actuation control pulses are also integrated on a capacitor to generate a voltage that is compared with a temperature dependent reference voltage selected to represent an incipient flood condition. When the capacitor voltage is detected as having increased to this reference voltage, the comparator causes an attenuation of the injector actuation control pulse. In one embodiment, the injector actuation control pulse is attenuated by being inhibited for the remainder of the cranking period after which the capacitor is suitably discharged. In another embodiment, the injector actuation control signal is inhibited until the capacitor is discharged at a predetermined rate to a level below the incipient flood level. And, in a third embodiment, the width of the injector actuation control signal is decreased by a one shot pulse the width of which varies with one or more engine parameters.