Methods and systems are provided for diagnosing degradation and/or alteration in an evaporative emission control system of a vehicle. In one example, a method may include, during a refueling, monitoring a fuel tank pressure and a fuel fill level, and detecting a presence or an absence of a fuel vapor canister of the EVAP system based on a change in fuel tank pressure with an increase in fuel level.

Methods and systems for diagnosing operational status of a carbon filled canister heater are described. The methods and systems may include activating an evaporative emissions system heater, a pump, and a canister purge valve to determine if long chain hydrocarbons are released from a carbon filled canister. Release of long chain hydrocarbons from the carbon filled canister may be indicative of desired operation of a carbon filled canister heater.

Methods and systems are provided for indicating whether a canister purge valve in a vehicle evaporative emissions control system is degraded. In one example, an air intake system hydrocarbon (AIS HC) trap temperature may be monitored during a refueling event, and responsive to an indication that the AIS HC trap temperature change is greater than a predetermined threshold, it may be indicated that the canister purge valve is degraded. In this way, diagnosis of whether a vehicle canister purge valve is degraded may be indicated without the use of engine manifold vacuum, and may be advantageous for vehicles configured to operate for significant amounts of time without engine operation, or without intake manifold vacuum.

Methods and systems for diagnosing operation of an evaporative emissions system are described. The methods and systems may include increasing an amount of vacuum stored in an evaporative emissions system during discontinuously operating an engine in a boosted operating mode. Storing vacuum allows the evaporative emissions system to reach a desired vacuum level to verify absence of an evaporative emissions system breech.

Methods and systems are provided for diagnosing a heating element coupled to a canister of an evaporative emissions control (EVAP) system. In one example, a method (or system) may include evacuating the canister at different temperature conditions, and diagnosing the heating element based on the different times taken to evacuate the canister at the different temperature conditions.

Methods and systems are presented for operating a refueling valve of an evaporative emissions system. The methods and systems may attempt to reactivate a refueling valve that has stuck due to the refueling valve being exposed to liquid fuel. In one example, a voltage that is applied to the refueling valve may be increased to reactivate the refueling valve.

A fuel vapor treatment apparatus includes a controller configured to detect an abnormality in at least one of a first check valve, a second check valve, a second purge passage, a charging passage, and an ejector based on pressure detected by a pressure detector.

A vehicle includes a fuel tank, a canister, a first valve, a second valve, a heater, and a controller. The fuel tank is configured to store fuel. The canister is in fluid communication with the fuel tank and is configured to receive and store evaporated fuel from the fuel tank. The first valve is disposed between the fuel tank and the canister. The second valve is disposed between the canister and ambient surroundings. The heater is disposed within the canister. The controller is programmed to, periodically initiate diagnostic tests that are configured to determine if the heater is operating properly, if the heater is unable to turn off, or if the heater is unable to turn on.

A straddled vehicle on which a part used for performing an inspection for a leak of gas from an evaporative emission system is mounted such that a weight balance of the straddled vehicle is maintained and mass concentrates includes a canister-integrated-leak-detection device that detects a leak of gas from an evaporative emission system. The canister-integrated-leak-detection device configured in a state where at least one of a vent valve or a suction pump is integrated with a canister is supported via a common attaching member to intersect with at least one of a virtual-left-right-center plane that includes a center in a left-right direction and is perpendicular to the left-right direction, a virtual-front-rear-center plane that includes a center in a front-rear direction and is perpendicular to the front-rear direction, or a virtual-up-down-center plane that includes a center in an up-down direction and is perpendicular to the up-down direction in the vehicle.

A gas-leak-detection device for detecting a gas leakage from an evaporative emission system includes an electric-wire-connection portion and a passage connection portion that are disposed to overlap with at least one of appearance components in a vehicle when the vehicle is seen in a viewing direction, and are disposed closer to the at least one appearance component than a center plane perpendicular to the viewing direction when the vehicle is in an upright state, the center plane being one of an imaginary-lateral-center plane that is an imaginary vertical plane perpendicular to the left-right direction, an imaginary-longitudinal-center plane that is an imaginary vertical plane including a center in the front-rear direction and being perpendicular to the front-rear direction, or an imaginary-vertical-center plane that is an imaginary horizontal plane including a center in the top-bottom direction and being perpendicular to the top-bottom direction.