Patent ID: 6016792
Filing Date: 2000-01-25
Classification: F02M

Abstract:
A leak test system for a vaporized fuel treatment mechanism, comprising:a fuel tank for supplying fuel to an engine mounted on a vehicle,an intake passage for aspirating air for combustion in said engine,a throttle provided in said intake passage for adjusting an amount of a flowing in said intake passage,a canister for adsorbing vaporized fuel,a first passage for leading vaporized fuel from said fuel tank into said canister,a first valve for opening and closing said first passage,a second passage connecting said canister and intake passage downstream of said throttle,a second valve for opening and closing said second passage,a third valve for introducing atmospheric air into said canister,a sensor for detecting a pressure in a flowpath section from said fuel tank to said second valve via said first passage, canister and second passage, anda microprocessor programmed to:open said second valve,lead negative pressure in said inlet pipe into said flowpath section,close said second valve so as to close said flowpath section with negative pressure therein,determine if there is a leak in said flowpath section based on a pressure variation in said section after said section has been closed,measure a pressure variation rate in a predetermined time interval after said section has been closed,set, in said predetermined time interval, a reference value larger by a predetermined amount than a minimum value of the variation rates which have been measured,determine that there is sloshing in said fuel tank when a latest variation rate exceeds said reference value, andstop determining of the leak when there is sloshing.