Fuel consumption compensation for evaporative emissions system leak detection methods

A method for monitoring an evaporative emissions control (EVAP) system in a vehicle, wherein said EVAP system includes a vent valve operable to an open state that allows fluidic communication through the vent valve between the fuel tank and atmospheric pressure, and a closed state that blocks fluidic communication through the vent valve;

• and a purge valve operable to an open state that allows fluidic communication through the purge valve between the fuel tank and engine vacuum, and a closed state that blocks fluidic communication through the purge valve, said method comprising:
• establishing a leak test pressure in the EVAP system;
• operating the vent valve and the purge valve to the closed state;
• determining an actual pressure change of EVAP system pressure;
• determining an expected pressure change of EVAP system pressure based on vehicle operating conditions that include the fuel consumption amount;
• and
• indicating that a leak is detected if the actual pressure change differs from the expected pressure change by more than a difference threshold.