Patent ID: 6679230
Filing Date: 2004-01-20
Classification: B60K,B60W,F02M,Y02T

Abstract:
A diagnostic apparatus for an evaporated fuel system in which fuel vapor, evaporated from fuel within a fuel tank, is adsorbed, and the adsorbed fuel vapor is purged into an intake passage of an internal combustion engine via a purge passage by using a negative pressure of the intake passage, comprising:a pressure introduction unit introducing a negative pressure of an intake passage of the engine into a fuel tank to cause an evaporated fuel system pressure to reach a reference pressure; a count detection unit determining, before a start of execution of a malfunction determination of the evaporated fuel system, one of a time count and a total of purged fuel flow rate after a start of the introduction of the negative pressure; and a control unit changing said one of the time count and the total of purged fuel flow rate, determined by the count detection unit, depending on whether an internal pressure in the intake passage of the engine after the start of the introduction of the negative pressure exceeds a threshold value.