A vaporized fuel treatment device includes a sealing valve disposed in a vapor passage between a fuel tank and a canister and including a valve element that moves in an axial direction with respect to a valve seat, a cut-off valve that cuts off a communication between the canister and an atmosphere, a pump that reduces an internal pressure of the canister, a vapor passage diagnostic module that decreases an internal pressure of the fuel tank by the pump via the canister so as to diagnose whether leakage occurs in the vapor passage in a state where the communication between the canister and the atmosphere is cut off and the sealing valve is opened, and a learning module that executes a learning of a valve opening start position of the sealing valve based on a change in the internal pressure of the fuel tank when changing an axial distance between the valve element and the valve seat when the internal pressure of the fuel tank is equal to or smaller than a predetermined value after a diagnosis of leakage in the vapor passage.

Methods and systems are provided for cleaning a fuel vapor storage canister positioned in an evaporative emissions control system of a vehicle. In one example, a method comprises sealing a fuel system of the vehicle for descending an altitude change that is predicted in advance, and subsequent to the vehicle descending the altitude change, unsealing the fuel system to passively purge fuel vapors stored in the fuel vapor storage canister to a fuel tank of the vehicle. In this way, bleed through emissions from the fuel vapor storage canister may be reduced, and engine operation may be improved.

Embodiments for controlling fuel vapors are provided. In one example, a method comprises initiating a purge of a fuel vapor canister responsive to a temperature profile at a vent side of the fuel vapor canister. In this way, release of fuel vapors to the atmosphere may be reduced.

A system includes a diagnostic module that selectively performs a purge valve leak diagnostic to diagnose a leak in a purge valve in a fuel system of a vehicle. Performing the purge valve leak diagnostic includes determining a level of vacuum in a fuel tank. A control module determines at least one operating condition associated with the vehicle. The at least one operating condition corresponds to an operating condition that affects the level of vacuum in the fuel tank. The control module, based on the at least one operating condition, selectively modifies the purge valve leak diagnostic. Selectively modifying the purge valve leak diagnostic includes at least one of preventing the diagnostic module from performing the purge valve leak diagnostic, preventing the diagnostic module from completing the purge valve leak diagnostic, and causing the diagnostic module to indicate that a result of the purge valve leak diagnostic was indeterminate.

An abnormality detection device of an internal combustion engine includes an ECU that is an abnormality detection unit detecting a leakage occurrence of a second pure pipe. When the internal combustion engine is in a supercharging operation state that a supercharger operates and the second purge pipe is closed by a second purge valve, the ECU detects the leakage occurrence of the second purge pipe based on a differential pressure between a pressure in the second purge pipe and an atmospheric pressure. In this case, the valve pressure in the second purge pipe is a pressure in the second purge pipe between the second purge valve and the intake pipe.

Methods and systems are provided for diagnosing functionality of a check valve in a vehicle evaporative emissions system, where the check valve functions to prevent unmetered air from entering engine intake under conditions of engine intake manifold vacuum. In one example, a method may include diagnosing whether the check valve is stuck open based on a temperature change at the fuel vapor canister as monitored by a canister temperature sensor, and responsive to an indication that the check valve is stuck open, taking mitigating actions to reduce undesired emissions. In this way, functionality of such a check valve may be determined periodically, without additional sensors, thus reducing costs while improving emissions.

An abnormality detection device for an engine system detects an abnormality in a fuel vapor pipe connected to an intake pipe of an engine at a portion upstream of a supercharger in a flow direction of intake air. The abnormality detection device includes an intake air temperature sensor and an abnormality detection portion. The intake air temperature sensor is fitted to the intake pipe on an upstream side of the supercharger in the flow direction of intake air and detects a temperature of intake air mixed with fuel vapor introduced into the intake pipe from the fuel vapor pipe. The abnormality detection portion detects an abnormality in the fuel vapor pipe according to a detection value of intake air detected by the intake air temperature sensor.

An ECU functioning as a diagnostic device includes an information acquisition portion acquiring a flow rate of a fluid flowing through an intake pipe, and a diagnostic portion performing a diagnosis on a second purge pipe employed as a fuel gas pipe regarding a connection failure. The diagnostic portion diagnoses a connection failure of the fuel gas pipe according to magnitude of a pulsation of the flow rate acquired by the information acquisition portion.

A fuel vapor treatment apparatus is provided with an air-fuel-ratio obtaining portion and a clogging determining portion. The air-fuel-ratio obtaining portion obtains the air-fuel ratio. The clogging determining portion determines whether a purge line is clogged based on a maximum variation amount of air-fuel ratio. In a case where no clogging is occurred in the purge line, the air-fuel ratio significantly fluctuates temporarily. In a case where at least a part of the purge line is fully clogged, even when a purge valve receives a valve opening command to be opened, fuel vapor cannot be introduced into the engine, so that the air-fuel ratio is not varied. In view of an air-fuel ratio variation, it is determined whether the purge line is clogged.

A method and a device for diagnosing a ventilation line of a motor vehicle are provided. The ventilation line is arranged between a fuel tank and an activated carbon filter. The motor vehicle has a control unit (ECU) and is powered by an internal combustion engine. The state of a vacuum switch is evaluated for the diagnosis.