Abstract: An oil retaining amount determination device includes a collected-liquid tank, an element, a thermistor, and a control unit. The collected-liquid tank is arranged in a supply line of CNG. The element separates oil from the CNG that flows into the collected-liquid tank. The thermistor is arranged in a downward direction from the element in the collected-liquid tank and generates heat by being electrified. The control unit determines whether the thermistor is immersed in the oil based on change of a thermistor voltage at the time of electrification of the thermistor. The control unit performs the determination procedure when flow of the CNG in the supply line is stopped.

Abstract: In a fuel injection control device, a learning value compensating for a steady deviation between actual air-fuel ratio and target air-fuel ratio is updated through an air-fuel ratio feedback control during engine operation, and a fuel injection amount is corrected using the learning value. If fuel having been replenished is detected at the time of engine starting, a correction amount is added to the learning value. Here, in a case where the learning value is a value which is included in a predetermined range, the correction amount is set to “0” and engine starting is performed by using the learning value as it is. Meanwhile, in a case where the learning value is a value which is not included in the predetermined range, the learning value is corrected to a value equal to a boundary value of the predetermined range by the correction amount, and engine starting is performed.

Abstract: A fuel supply apparatus is applied to a multi-fuel engine. The multi-fuel engine is constructed such that the operation mode of the engine can be switched, while the engine is operating, between a liquid fuel operation mode, in which fuel is supplied by injecting a liquid fuel into an intake passage, and a gas fuel operation mode, in which fuel is supplied by injecting a gas fuel into intake air. The fuel supply apparatus is equipped with a control device that performs a decreasing correction of the injection amount of the gas fuel when the engine operation mode is switched from the liquid fuel operation mode to the gas fuel operation mode.