A pressure sensor malfunction determination device for a fuel tank includes a fuel tank that stores fuel, a canister that absorbs an evaporated fuel gas and includes a drain port opened to atmosphere, an evaporation path communicating with the canister and fuel tank, a purge gas path communicating with an engine inlet system and the canister, a pressure sensor that detects a pressure, a solenoid valve that opens/closes the evaporation path, and a control unit that controls an opening/closing state of the solenoid valve. When the fuel tank pressure is one of predetermined positive and negative pressure states, the control unit performs valve-opening control on the solenoid valve. The control unit includes a pressure sensor malfunction determination unit that, when an output value of the pressure sensor detected under an atmospheric pressure condition corresponds to a pressure other than the atmospheric pressure, determines that the pressure sensor is malfunctioning.

An evaporated fuel processing apparatus is provided with an initializer configured to increase a step number with which a stepping motor is rotated in a valve closing direction, when there is an initialization request for the blocking valve and tank pressure of the fuel tank is in a predetermined pressure range near atmospheric pressure, in comparison with when the tank pressure is out of the predetermined pressure range.

An improved evaporative emission mitigation system for a motor vehicle includes a canister filled with an adsorbent material connected to a membrane module. The membrane module contains a membrane that separates gaseous hydrocarbons from inert air components within fuel vapor generated by the evaporation of fuel due to the heating of the motor vehicle. The gaseous hydrocarbons separated by the membrane are returned to the canister, where they will again be adsorbed by the adsorbent material. The inert air components are vented from the membrane module into the open atmosphere outside of the motor vehicle.

In at least some implementations, a charge forming device for a combustion engine includes a housing, a throttle valve and a vent valve. The housing has an inlet chamber in which a supply of fuel is received, a vent passage communicating with the inlet chamber and a throttle bore with an inlet through which air is received. The throttle valve is carried by the housing and has a valve head movable relative to the throttle bore to control fluid flow through the throttle bore. And the vent valve is electrically actuated, carried by the housing and has a valve element that is movable between an open position wherein fluid may flow from the inlet chamber through the vent passage and a closed position where fluid is prevented or inhibited from flowing out of the inlet chamber through the vent passage.

In a fuel vapor treatment apparatus, when an internal combustion engine is in non-turbocharging operation, a controller is configured to open a first valve and a second valve, and when the internal combustion engine is in turbocharging operation, the controller is configured to close the first valve, and to open a third valve based on pressure in a fuel tank detected by a first pressure detector.

An evaporative emissions isolation module system configured to manage venting on a fuel tank system is disclosed. The isolation module system includes a carbon canister, a multi-valve assembly and a controller. The carbon canister is adapted to collect fuel vapor emitted by the fuel tank and to subsequently release the fuel vapor to the engine. The multi-valve assembly includes a motor drive that rotates a camshaft having at least a first cam and a second cam housed in a manifold. The multi-valve assembly has a first valve and a second valve. The first valve selectively fluidly connects the fuel tank and the carbon canister. The second valve fluidly connects the carbon canister with a vent port defined in the manifold that vents to atmosphere. The controller sends signals to the multi-valve assembly based on operating conditions to open and close at least one of the first and second valves.

An evaporated fuel processing device is configured to collect evaporated fuel from a fuel tank of an internal combustion engine. The evaporated fuel processing device includes the fuel tank, a canister, a tank sealing valve, a switching valve, and a differential pressure sensor. The fuel tank stores fuel for the internal combustion engine. The canister adsorbs evaporated fuel generated in the fuel tank. The switching valve switches between allowing and blocking off communication between the canister and open air. The differential pressure sensor detects a system differential pressure between the pressure on the canister side of the tank sealing valve and the pressure on the fuel tank side of the tank sealing valve in the detection target system.

Methods and systems are provided for refilling a fuel tank devoid of fuel vapors. In one example, a method may include, prior to an upcoming refueling event, conditioning a fuel vapor-less fuel tank by operating a fuel pump. Operation of the fuel pump may agitate and vaporize the residual fuel in the fuel tank.

Both an improvement in detection accuracy of a valve opening position of a blocking valve and a reduction in time required for learning of the valve opening position are achieved. An evaporated fuel processing apparatus is provided with a learning device configured to learn the valve opening position of the blocking valve. The learning device learns the valve opening position (i) by stepwisely increasing a stroke amount by rotating a stepping motor by two steps at each time in a valve opening direction and (ii) by determining whether a difference between the stroke amount at present and the stroke amount corresponding to the valve opening position is one step of rotation of the stepping motor, or two steps, on the basis of pressure fluctuation on the canister side of the blocking valve associated with the rotation of the stepping motor when the blocking valve is opened, when learning the valve opening position.

Methods and systems are provided for conducting a diagnostic on a fuel tank isolation valve that regulates a flow of fuel vapors from a fuel tank to an evaporative emissions system. In one example, a method comprises determining whether the fuel tank isolation valve is stuck in a first open position or a second open position based on a time duration between commanding open a canister purge valve to direct fuel vapors to an engine, and an exhaust gas sensor indicating a rich air-fuel ratio. In this way, appropriate mitigating action may be taken in response to the fuel tank isolation valve being stuck in either the first open position or the second open position.