Methods and systems are provided for indication of a degradation in an EVAP and/or fuel system. In one example, a method for indication of a presence or absence of a degradation in a refueling system may include vacuum pull-down and pressure bleed-up tests being carried out based on a state of submersion of a spud valve in liquid fuel in a fuel tank.

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.

A control unit diagnoses a failure of a fuel storage unit that seals a fuel tank and a processing unit that processes fuel evaporative gas in the fuel tank. A first pressure detection unit of the fuel storage unit detects the pressure of the fuel tank. A second pressure detection unit of the fuel storage unit is disposed at a position different from the first pressure detection unit, and detects the pressure of the fuel tank. The control unit specifies a failure portion of the fuel storage unit and the processing unit based on a change in either one or both of a first pressure value detected by the first pressure detection unit and a second pressure value detected by the second pressure detection unit when the pressure of the fuel tank is changed.

Disclosed is a device for evaporating vapors of a fuel stored in a motor vehicle tank. The evaporation device includes a bypass circuit and a bypass valve configured to move between a so-called “absorption” position, in which the bypass valve allows the gases to flow between the tank and an absorbent filter and a so-called “leak detection” position, in which the bypass valve allows the gases to flow between a purge circuit and the tank via the bypass circuit.

A method and device for diagnosing a leak in an evaporation system and in a tank ventilation line of an internal combustion engine is disclosed. The method includes diagnosing the entire evaporation system using a fresh-air shut-off valve of the evaporation system and a pressure sensor system of the evaporation system. During the check on whether there is a leak in the evaporation system of the internal combustion engine, a separate check of different diagnosis regions of the evaporation system is undertaken, where one of these diagnosis regions is a tank region of the internal combustion engine and a further diagnosis region is a filter region of the internal combustion engine. During the diagnosis of the tank ventilation line, the flow through the tank ventilation line is checked.

When a leak test for a purge pipe and a vapor pipe as targets is executed, a sealing valve that is being closed is opened while an open state of a bypass valve is kept prior to the execution of the leak test, fuel evaporative gas in a fuel tank is caused to flow out to a canister side to reduce a tank internal pressure Ptan to a valve opening guarantee determination value P0, and after the bypass valve is closed subsequently, the leak test is started.

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 regulating evaporative emissions from a fuel system. In one example, a method may comprise spinning an engine unfueled responsive to a hydrocarbon concentration at a fresh air end of a fuel vapor canister increasing above a first threshold. The method may comprise spinning the engine to pull hydrocarbons away until a hydrocarbon concentration at a purge end of the fuel vapor canister, opposite the fresh air end, increases above a second threshold.

Methods and systems are provided for conducting a diagnostic routine of the fuel vapor system using pressure generated by raising or lowering a vehicle body element such as a hood or a trunk. In one example, by utilizing lift gate cylinders coupled to the hood or trunk, during raising a hood or trunk, the fuel vapor system may be evacuated and during lowering the hood or trunk, the fuel vapor system may be pressurized. A change in vacuum or higher pressure in the fuel vapor system may be monitored over a time period to detect any undesirable evaporative emissions from the fuel vapor system.

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.