Whether or not to specified vacuum pressure after decreasing

摘要

PROBLEM TO BE SOLVED: To prevent the misjudgment of a leak by making a judgment on the leak until the evaporating fuel is more produced in the fuel tank by the fuel which is returned to the fuel tank when an engine is operated. ;SOLUTION: A fuel tank 7 is joined to a surge tank 5 by a purge passage 21 and, after the pressure of evaporating fuel in the purge passage 21 is reduced to a prescribed negative pressure, it is judged whether a leak is produced in the purge passage 21 or not in response to the degree of increase in the pressure in the purge passage 21 in a hermetically sealed state which is shut from the atmosphere. The judgment is made until the evaporating fuel is more produced in the fuel tank 7 by the fuel which is returned to the fuel tank when an engine 1 is operated, which can ensure enough time for judging if a leak is produced and thus prevent the misjudgment of the leak.;COPYRIGHT: (C)1997,JPO