Patent ID: 7481101

Claim:
An evaporated fuel treatment device of an internal combustion engine having a canister that adsorbs evaporated fuel generated in a fuel tank for treatment, comprising: a sealing valve that is disposed between said fuel tank and said canister and controls a communication state between said fuel tank and said canister; tank internal pressure control means that issues a valve opening instruction to said sealing valve when tank internal pressure reaches a predetermined positive valve opening pressure while said sealing valve is closed; decompression presence/absence determination means that determines whether said tank internal pressure is reduced in response to the valve opening instruction by said tank internal pressure control means; and closing failure determination means that determines closing failure of said sealing valve when there is no sign of said reduction in the tank internal pressure under a condition in which said tank internal pressure reaches said predetermined positive valve opening pressure, thereby said valve opening instruction is issued to said sealing valve.