Patent ID: 7165447
Filing Date: 2007-01-23
Classification: F02M

Abstract:
1. A failure diagnostic apparatus for a fuel vapor purge system adsorbing in a canister fuel vapor generated in a fuel tank and purging the adsorbed fuel vapor into an intake system, comprising: pressure difference generation means for generating, when failure diagnosis is executed, a pressure difference between respective pressures inside and outside a fuel vapor path including said fuel tank and said canister; failure diagnostic means for comparing, with a predetermined reference pressure, the pressure inside said fuel vapor path when said pressure difference generation means generates said pressure difference, for conducting said failure diagnosis to determine whether failure occurs or not based on result of the comparison; execution determination means for determining, based on whether or not an amount of fuel vapor in said fuel vapor path is smaller than a predetermined reference amount, whether or not said failure diagnosis is to be executed by said pressure difference generation means and said failure diagnostic means; and said execution determination means determines, when an amount of fuel vapor adsorbed in said canister is smaller than a first predetermined amount, that said amount of fuel vapor in said fuel vapor path is smaller than said predetermined reference amount.