Methods and systems are provided for detecting a fuel tank oil-canning event during conditions when a vacuum is applied to the fuel tank, such as during a fuel system leak test or during purging of a fuel system canister. In one example, a method may include comparing the fuel tank pressure changes during a leak test to changes in fuel tank temperature or fill level and indicating fuel tank oil-canning in response to a higher than threshold rise in fuel tank pressure during or following application of vacuum to the fuel tank while each of a fuel temperature and fill level remain unchanged. By detecting fuel tank oil-canning accurately, appropriate countermeasures can be taken.