Methods and systems are provided for adjusting and diagnosing one or more canister purge valves in a fuel vapor recovery system. In one example, a method may include adjusting one or more canister purge valves in a passage coupled to a fuel vapor canister of the fuel vapor recovery system to allow flow between an intake passage and an intake manifold of the engine based on engine operating conditions. Further, the method may include indicating the one or more canister purge valves are degraded and based on a change in air-fuel ratio after adjusting the one or more canister purge valves.