US Patent 11274622 Methods and systems for diagnosing fuel system degradation

Methods and systems are provided for diagnosing leaks in a fuel system. In one example, a method may include monitoring a fuel level in a vehicle fuel tank of the fuel system during refueling and indicating degradation of the vehicle fuel tank and/or a bellows coupled to the vehicle fuel tank based on the monitored fuel level. In some examples, indicating the degradation may further be based on a rate of fuel supplied to the vehicle fuel tank during the refueling and/or a vehicle fuel economy. In this way, degradation to the vehicle fuel tank and the bellows may be passively determined with minimal specialized components in the fuel system.