Methods and systems are provided for a fuel system. In one example, a method may include cleaning an orifice of an ELCM. The cleaning includes adjusting a position of a valve in a passage to fluidly couple a reference orifice of the ELCM to an intake manifold.

Methods and systems are provided for adjusting a volume of a variable volume device arranged in a fuel tank. In one example, a method may include, upon conditions being met, operating a pump of an evaporative emissions control (EVAP) system leak detection module (ELCM) to increase or decrease the volume of the variable volume device in response to a refueling event of a vehicle being transported.

The failure diagnosis apparatus whether or not a failure exists in a fuel-evaporation-gas purging system that a negative pressure in an intake system of an internal combustion engine is introduced into an accumulator and pressure accumulation is performed in a time period from a time when a driver turns off an ignition key to a time when the internal combustion engine stops its rotation, that the accumulated negative pressure is introduced into a fuel-evaporation-gas path before the internal combustion engine stops the rotation or after the internal combustion engine has stopped the rotation, and that in a time from a time when after the internal combustion engine has stopped the rotation, the driver again turns on the ignition key to a time when the internal combustion engine starts, it is determined whether or not a pressure change in the fuel-evaporation-gas path exists.

A method of detecting a leak in an evaporative emissions system includes sealing an evaporative emissions system, achieving a first target pressure in the evaporative emissions system, achieving a second target pressure in the evaporative emissions system after achieving the first target pressure, and monitoring a system pressure subsequent to the second target pressure achieving step to determine a leak condition of the evaporative emissions system.

A leak detection module (LDM) includes a housing, a canister valve solenoid (CVS) that is arranged within the housing and in fluid communication along a first fluid passageway between first and second ports. The module also includes a pump that is arranged within the housing and is in fluid communication with the first and second ports, and a pressure sensor that is in fluid communication with at least one of the first and second ports. A first controller is arranged in the housing and is in communication with the pump, the CVS and the pressure sensor. The first controller runs a test procedure using the pump and operating the CVS between open and closed positions to monitor a pressure within the module. The first controller communicates a result based upon the monitored pressure to a second controller that is arranged outside the housing and remotely from the module.

Methods and systems are provided for executing a leak test diagnostic of a variable volume fuel tank. In one example, a method includes diagnosing a presence of an absence of a leak in a bellows via actuating a bellows valve fluidly coupling the bellows to a vapor canister during a key-off event.

A module (14) for detecting a leakage, comprising a pressure sensor (8) and a pump (2) for generating pressure, is characterized in that, regarding the object of detecting and/or quantifying a leakage of an arrangement which has a large sealed volume, in a reliable manner with a compact device, the module (14) has a sealable reference volume (11) which can be connected in terms of flow by means of a valve (9) to a tank connection (10) and which can be disconnected therefrom in a flow-tight manner, wherein the pressure inside the reference volume (11) can be detected by the pressure sensor (8), wherein pressure can be generated inside the reference volume (11) by means of the pump (2) and wherein the reference volume (11) can be connected in a flow-conducting manner by means of a shut-off valve (4) via a reference aperture (5) with a defined flow cross section to an atmosphere outlet (1) and can be disconnected therefrom.

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 for a vehicle may comprise, during a refueling event, detecting presence or absence of a fuel vapor canister coupled to a vent line of the evaporative emission control system of the vehicle based on a response of a hydrocarbon sensor coupled to the vent line. In this way, hydrocarbon emissions may be reduced by identifying vehicles with tampered or degraded evaporative emission control system.

A failure diagnosis method and a failure diagnosis system of a dual purge system may determine whether a closed stuck failure or an opened stuck failure occurs in a line forming a dual purge system by measuring a pressure in a negative pressure formation device and comparing the corresponding pressure with a predetermined reference value when a purge valve of the dual purge system is in an opened or closed state, and may determine whether the failure occurs in components related to a secondary purge line in the dual purge system in which it is difficult to determine whether the failure occurs in a conventional failure diagnosis method of a single purge system in a simple method.

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.