Patent ID: 6761058
Filing Date: 2004-07-13
Classification: F02M

Abstract:
A leakage determination system for an evaporative fuel processing system that causes a canister to absorb evaporative fuel generated from a fuel tank and supplies the evaporative fuel absorbed in the canister to an intake system of an internal combustion engine,the leakage determination system comprising: pressure detection means for detecting pressure within the evaporative fuel processing system; primary pressure reduction means for primarily reducing the pressure within the evaporative fuel processing system until the detected pressure becomes equal to a predetermined negative pressure, by introducing negative pressure from the intake system; secondary pressure reduction means for secondarily reducing the pressure within the evaporative fuel processing system by introducing the negative pressure from the intake system successively after the primary pressure reduction by said primary pressure reduction means under predetermined conditions; and leakage determination means for determining that there is a leak in the evaporative fuel processing system when a variation amount of the detected pressure detected during the secondary pressure reduction by said secondary pressure reduction is higher than a predetermined leakage reference value.