Patent ID: 6202478
Filing Date: 2001-03-20
Classification: F02M

Abstract:
A method of testing an evaporative emission control system for a fuel cap sealing problem comprising:detecting a refueling event;running a large leak test of said system to determine if a large leak is present;setting a large leak fault code and activating a driver warning lamp indicating a potential cap sealing problem if said large leak is detected;rerunning said large leak test repeatedly after said large leak is detected to determine when said large leak condition ceases;removing said large leak fault code and deactivating said driver warning lamp when said large leak condition ceases;detecting a next refueling event after said large leak is detected if said large leak condition has not ceased;rerunning said large leak test after said next refueling event;setting a persistent leak fault code indicating that said potential cap sealing problem had an opportunity to be corrected but was not if said large leak is again detected;suspending subsequent large leak tests until said persistent leak fault code is cleared; andsuspending said large leak test from running after two consecutive normal leak tests indicate a leak is present in said system.