Device for detecting canister deterioration

摘要

A fuel evaporation control system is connected to an engine control system in which an air-fuel ratio in mixture gas supplied to an engine is controlled to an optimum level. Fuel evaporated from a fuel tank is absorbed by a canister, and the absorbed fuel is purged into the engine. Deterioration of the canister in its air-permeability is detected based on measured pressure in the fuel evaporation control system or calculated density in the purge gas, both the pressure and the density being measured or calculated under two different amounts of purge gas flow. Deterioration of the canister in its fuel-absorbing ability is also detected based on the purge gas density.