Evaporative emissions system check valve monitor for GTDI engines

A method for a vehicle comprising:

• supplying fuel from a fuel system to an engine during a single drive cycle which comprises a duration between a key-on event and a key-off event;
• storing fuel vapors from the fuel system in an evaporative emissions system removably coupled to the fuel system;
• during the single drive cycle, evacuating the fuel system and evaporative emissions system through a first check valve in a first condition;
• during the single drive cycle, evacuating the fuel system and evaporative emissions system through a second check valve in a second condition;
• and
• indicating a presence or absence of gross undesired evaporative emissions in the fuel system and/or evaporative emissions system, and indicating whether one of the first check valve or the second check valve is stuck substantially closed, based on a vacuum level reached during the evacuating of the fuel system and evaporative emissions system in both the first condition and the second condition.

A system for a vehicle, comprising:

• a fuel system including a fuel tank, the fuel tank communicatively coupled to an evaporative emissions system comprising a fuel vapor canister;
• a canister vent valve, positioned in a vent line that couples the fuel vapor canister to atmosphere;
• a canister purge valve, positioned in a purge line stemming from the fuel vapor canister;
• a first check valve, positioned in a first conduit downstream of the canister purge valve, where the first conduit connects the purge line to an intake manifold of a vehicle engine;
• a second check valve, positioned in the purge line downstream of the canister purge valve and further downstream of the first conduit;
• an ejector system, positioned downstream of the second check valve;
• a compressor, positioned in an intake passage upstream of an air intake throttle, the air intake throttle positioned in the intake passage upstream of the intake manifold;
• a fuel tank pressure transducer positioned between the fuel tank and the fuel vapor canister;
• and
• a controller storing instructions in non-transitory memory, that when executed, cause the controller to:
• in a first condition where pressure in the intake manifold is less than barometric pressure, command closed the canister vent valve, command open the canister purge valve, and monitor pressure in the fuel system and evaporative emissions system;
• in a second condition where the compressor is activated and where pressure in the intake manifold is greater than barometric pressure, command closed the canister vent valve, command open the canister purge valve, and monitor pressure in the fuel system and evaporative emissions system;
• and
• indicate a presence or absence of gross undesired evaporative emissions in the fuel system and evaporative emissions system, and whether either the first check valve or second check valve is stuck closed, based on a vacuum level reached during monitoring pressure in the fuel system and evaporative emissions system in both the first and second conditions during a single drive cycle.