Malfunction test apparatus for fuel vapor purge system

摘要

A fuel vapor purge system connects a fuel tank with a canister and collects fuel vapor generated in the fuel tank by the canister. The purge system purges the collected fuel vapor to an intake passage of an internal combustion engine through a purge passage. A change of pressure due to fuel vapor generation in the fuel tank is measured while the purge passage is sealed. The pressure in the purge passage is differentiated from the pressure outside the purge passage and the purge passage is sealed. In this state, a change of the pressure in the purge passage is measured. After measuring the amount of generated fuel vapor, a test for leakage in the purge passage is performed based on the change of pressure due to the fuel vapor generation when measuring changes of pressure in the purge passage during a predetermined period.