Failure diagnosis device for a fuel pump

摘要

This device diagnoses whether or not a fuel pump which supplies fuel to an engine has failed. The pump includes a plurality of pressure chambers which in turn discharge fuel according to the rotation of an input shaft which turns together with the engine. The supply capacity of the fuel pump when one of the pressure chambers has failed so as not to be able to discharge fuel is set to a value lower than the maximum value of the fuel supply amount which is required by the engine. A mechanism is provided which decides whether or not the fuel supply requirement of the engine is being satisfied, and failure of the fuel pump is diagnosed based upon the result of this decision. Further, accurate diagnosis can be performed by detecting the power output of the engine for each cylinder individually, and by deciding upon fuel supply insufficiency for each cylinder individually according to variation of the output power for each cylinder individually.