A method for diagnosing a fault situation of a negative-pressure generation line using a fuel tank pressure sensor that detects the pressure of a fuel tank is provided. The method detects pressure in a fuel tank measured by a fuel tank pressure sensor when a turbocharger is operated for boosting and a purge valve is operated and diagnoses a current situation as a fault situation in which an engine negative-pressure generation line remains open when a pressure change value calculated based on the pressure difference of the fuel tank exceeds a reference value. A warning of a fault situation is then output when a fault is determined.

Methods and systems are provided for controlling a duty cycle of a purge valve configured to regulate a purge flow from a fuel vapor storage canister to an intake of an engine during canister purging events. In one example, a method includes controlling a duty cycle of a purge valve configured to regulate a purge flow from a fuel vapor storage canister to an intake of an engine during a canister purging event based on a degradation factor obtained by comparison of durations at which a predetermined pressure is reached in an evaporative emissions system at multiple purge valve activation levels. In this way, a flow map stored at a controller may be updated for controlling the purge valve during subsequent purging events.

A tank venting system for an internal combustion engine includes a tank, which is connected via a tank vent to a sorption reservoir for a temporary storage of fuel from a tank venting flow. A purge air pump is provided for feeding regenerated fuel from the sorption reservoir via a purge air flow into an intake air flow to the internal combustion engine. A controller is configured to control the purge air pump in such a way that the purge air flow can be adjusted with regard to its pressure, its mass and/or its volume, thus ensuring that a metering of the regenerated fuel via the purge air flow into the intake air flow takes place in accordance with an operating state of the internal combustion engine. A method for regenerating a sorption reservoir is also provided.

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.

Methods and systems are provided for depressurizing a fuel tank of a vehicle by routing fuel tank vapors to an engine for combustion. In one example, a method may include reducing a pressure in the fuel tank by routing vapors from the fuel tank through a portion of a fuel vapor storage canister and, in response to an indication of a condition of degraded engine stability, re-routing the vapors from the fuel tank through an entirety of the fuel vapor storage canister. In this way, under conditions of degraded engine stability, a rate at which fuel tank vapors are directed to the engine may be reduced, which may thus mitigate the condition of degraded engine stability without aborting the operation to reduce the fuel tank pressure.

A fuel tank venting system for a motor vehicle includes an outlet side of a tank venting valve connected to an inlet side of a first vent line and to an inlet side of a second vent line. An outlet side of the first vent line is connected to an intake manifold upstream from a throttle valve and downstream from an air filter, and an outlet side of the second vent line is connected to the intake manifold downstream from the throttle valve. A position sensor may be located at a first position and the first closing element has a detectable element. The position sensor is connected to an electronic control device to transmit signals. A position of the first closing element may be determined by means of the position sensor and the detectable element.

Methods and systems are provided for depressurizing a fuel tank of a vehicle by routing fuel tank vapors to an engine for combustion. In one example, a method may include reducing a pressure in the fuel tank by routing vapors from the fuel tank through a portion of a fuel vapor storage canister and, in response to an indication of a condition of degraded engine stability, re-routing the vapors from the fuel tank through an entirety of the fuel vapor storage canister. In this way, under conditions of degraded engine stability, a rate at which fuel tank vapors are directed to the engine may be reduced, which may thus mitigate the condition of degraded engine stability without aborting the operation to reduce the fuel tank pressure.

A method for diagnosing a purge valve of a canister purge system includes (a) determining whether a purge valve, which is installed on a purge pipe connecting a canister with an intake system of an engine, is open and whether a purge pump is running, wherein the purge pump is configured to pump evaporative emission captured in the canister toward the intake system, and (b) determining whether the purge valve is in a close stuck state, based on upstream pressure and downstream pressure of the purge pump, when the purge valve is open while the purge pump is running.

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 evaporated fuel processing device includes a canister to which evaporated fuel generated in a fuel tank adheres; a purge passage passed through purge gas and connecting the canister and an intake pipe of an engine; a purge control valve provided on the purge passage and controlling a supply amount of the purge gas to the intake pipe by changing a duty cycle; a pump provided on the purge passage and feeding the purge gas from the canister to the intake pipe; and a controller control the duty cycle of the purge control valve. The controller detects a pressure difference between pressures at upstream and downstream ends of the purge passage while the purge gas is supplied, and corrects the duty cycle based on a supply amount of the purge gas with respect to the duty cycle with no influence of the pump, by using the detected pressure difference.