SYSTEMS AND METHODS FOR CONDUCTING VEHICLE EVAPORATIVE EMISSIONS TEST DIAGNOSTIC PROCEDURES

Methods and systems are provided for conducting diagnostics to indicate whether a fuel system and/or an evaporative emissions system of a vehicle has a source of undesired evaporative emissions, or not. In one example, a method comprises conducting such a diagnostic via evacuating the fuel system to a target vacuum, then sealing the fuel system from atmosphere and monitoring a pressure bleed-up in the fuel system, and dynamically adjusting a pressure bleed-up threshold responsive to one or more conditions that impact the pressure bleed-up during the diagnostic, and indicating undesired evaporative emissions responsive to the pressure bleed-up reaching the adjusted pressure bleed-up threshold. In this way, interpretation of the results of such a diagnostic may be more robust, completion rates may improve, and engine operation may be improved.