SYSTEMS AND METHODS FOR VEHICLE FUEL SYSTEM AND EVAPORATIVE EMISSIONS SYSTEM DIAGNOSTICS

Methods and systems are provided for diagnosing a vehicle fuel system for a presence or absence of undesired evaporative emissions. In one example, a method comprises evacuating the fuel system of a vehicle to a variable vacuum target as a function of a volatility of fuel in a fuel tank positioned in the fuel system and a loading state of a fuel vapor storage canister configured for capturing and storing fuel vapors from the fuel tank. In this way, analysis of a pressure-bleedup portion of the diagnostic may be more reliable and completion rates of the diagnostic may be improved, while conducting the test in an environmentally fashion.