Patent ID: 6736116
Filing Date: 2004-05-18
Classification: F02M

Abstract:
A fuel vapor treatment system comprising:a fuel tank; a canister fluidly coupled to the fuel tank by a first pipe and configured to adsorb fuel vapor evaporated from the fuel tank; a drain cut valve operatively coupled to the canister to control air flow into the canister; a purge valve disposed in a second pipe fluidly coupled between the canister and an intake passage of an internal combustion engine into which fuel vapor flows from the canister; a sensor configured and arranged to detect absolute pressure inside at least one of the first and second pipes; and a failure diagnosis device configured and arranged to set a reference pressure used for failure diagnosis of the drain cut valve while the purge valve is closed, the failure diagnosis device being further configured to calculate a pressure difference between the reference pressure and an absolute pressure inside at least one of the first and second pipes detected by the sensor after purging commences and to determine if the drain cut valve has failed based on the pressure difference.