Methods and systems are provided for diagnosing leaks/degradation in a fuel system. In one example, a system for a vehicle may comprise a variable volume device disposed within a fuel tank; an atmospheric port of the variable volume device fluidly coupled to a vent line upstream of a hydrocarbon sensor housed in the vent line, the vent line coupling a fuel vapor canister to atmosphere; and a controller storing instructions for monitoring output of the hydrocarbon sensor; and generating an indication of a degradation in the variable volume device based on the monitored hydrocarbon sensor. In this way, it is possible to effectively detect a degradation/leak in the variable volume device with minimal specialized components in the fuel system.

A valve member provides for the flow of vapors from a fuel tank of an internal combustion engine to escape the fuel tank. The valve member may include a valve and a boss or spacer. The valve is configured to selectively control the flow of vapor from the fuel tank. The boss or spacer is positioned in a predetermined relationship to the valve, and the boss or spacer prevents a deformation of the valve from disrupting the selectively controlled flow of vapor from the fuel tank.

A fuel system, a vehicle, and a method of controlling an evaporative emissions system for the vehicle are provided. The fuel system has a fuel tank having a fuel fill port with a closure member. An evaporative emissions canister has a first port fluidly coupled to the fuel tank to receive vapor therefrom and a second port, with the canister positioned between an air intake for an engine and a vent to atmosphere. A filter or a second canister is supported by a bracket for movement between first and second positions, with the filter fluidly coupling the second port of the canister to the vent in the first position, and the filter spaced apart from and decoupled from the second port of the canister in the second position. The second port of the canister is in direct fluid communication with atmosphere when the filter is in the second position.

A vehicle canister device includes a main canister including an inlet port through which evaporative gas is introduced from a fuel tank, an outlet port through which the evaporative gas introduced during operation of an engine is discharged to an intake side of the engine, and an internal space for filling activated carbon. The vehicle canister device also includes an auxiliary canister mounted in fluid-communication with the main canister and configured to allow external air to flow into the main canister through an atmosphere port provided on the main canister or the evaporative gas to flow therethrough upon stop of the engine. The auxiliary canister includes a plurality of activated carbon layers each filled with an activated carbon and a plurality of air layers disposed between the activated carbon layers.

Methods and systems are provided for performing a reverse purge of an evaporative emissions canister in a vehicle with a sealed variable volume fuel tank. In one example, a method may comprise in response to an ambient temperature reducing during a diurnal temperature cycle, and further in response to the EVAP canister loaded with fuel vapors above a threshold, closing a valve positioned at an atmospheric port of the fuel tank and opening a fuel tank isolation valve. In one example, the fuel tank isolation valve may be in fluid communication between the fuel tank and the EVAP canister. In this way, it is possible to convert a sealed variable volume fuel tank to a vented pressurized fuel tank and initiate a reverse purge during the cooldown hours of the diurnal temperature cycle.

Methods and systems are provided for aging a new plastic fuel tank in a vehicle. In one example, during a plug-in event to recharge a battery of the vehicle, the fuel tank is isolated and the fuel pump is actuated to agitate fuel within the tank and increase fuel vapors until the plastic fuel tank becomes aged to a predetermined degree by fuel vapors generated therein. In this manner, the fuel tank is aged more rapidly, resulting in more accurate fuel level readings and less noise and vibration.

Methods and systems are provided for indicating a restriction in a fuel system vapor recovery line. Responsive to such an indication, methods and systems are provided for taking mitigating actions such that an entirety of a vehicle fuel system and evaporative emissions system, including a fuel filler system, may be diagnosed as to a presence or absence of undesired evaporative emissions, even with the restriction in the vapor recovery line present. In this way, undesired evaporative emissions may be reduced or avoided, completion rates for such tests may be increased, and customer satisfaction may be improved.

A fuel tank system constructed in accordance to one example of the present disclosure includes a fuel tank and an evaporative emissions control system. The evaporative emissions control system is configured to recapture and recycle emitted fuel vapor. The evaporative emissions control system includes a liquid trap, a first device, a second device, a control module and a G-sensor. The first device is configured to selectively open and close a first vent. The second device is configured to selectively open and close a second vent. The control module regulates operation of the first and second devices to provide over-pressure and vacuum relief for the fuel tank. The G-sensor provides a signal to the control module based on a measured acceleration.

A hybrid vehicle evaporation system may include a fuel tank having a fuel level sensor, a refuel button, and a controller. The controller may be programmed to disable HV charging in response to a selection of the refuel button, monitor a fuel level received from the fuel level sensor, and enable HV charging in response to the fuel level failing to increase for a predetermined amount of time.

In a method for operating a tank device of a motor vehicle, with the tank device having a tank and a tank ventilation device with at least one switching valve, an excitation current can be applied to the switching valve, and the switching valve opens only when the excitation current exceeds an excitation current threshold over a certain period of time. Provision is hereby made to apply an excitation current which is greater than the excitation current threshold, at least temporarily, in a first mode of operation to the switching valve for heating purposes, also when ventilation of the tank is not governed by a control unit of the tank device.