A method and a device for diagnosing a ventilation line of a motor vehicle are provided. The ventilation line is arranged between a fuel tank and an activated carbon filter. The motor vehicle has a control unit (ECU) and is powered by an internal combustion engine. The state of a vacuum switch is evaluated for the diagnosis.

Methods and systems are provided for diagnostics of a fuel system configured with a three-way isolation valve and a four port canister. An example method includes, during a refueling event, indicating degradation of the three-way isolation valve based on pressure in the fuel tank during depressurization followed by refueling.

Methods and systems are provided for conducting an evaporative emissions test on a fuel system and an emissions control system in a vehicle. In one example, in response to an indication that a vehicle parking condition may result in the isolation of the fuel system from the emissions control system via the unintentional closing of fuel tank valves, a vehicle's active suspension system may be employed in order to level the vehicle a determined amount such that the fuel system isolation issues may be mitigated prior to an evaporative emissions test procedure. In this way, the entire fuel system and emissions control system may be diagnosed for potential undesired emissions, and potential violations of regulatory requirements for evaporative emissions testing may be reduced.

A method actuates a dosing valve of a tank ventilation system. The dosing valve is opened not only once but twice at every activation time, and thus a generated pressure wave is depleted. An associated tank ventilation system and an associated motor vehicle make use of the method.

An evaporated fuel treatment apparatus includes an abnormality determination unit that determines an abnormality of a purge passage. The abnormality determination unit changes an operating cycle of a purge control valve to a cycle longer than an initial set value while maintaining a duty ratio of the purge control valve set according to an operating state of an internal combustion engine, and determines an abnormality of the purge passage based on a first variation range and a second variation range calculated from a detection value detected by an airflow meter before and after the change of the operating cycle.

Various embodiments include a method for operating a fuel evaporation retention system of a vehicle with an internal combustion engine. It includes measuring a pressure change resulting from a temperature change of a gas volume in the fuel tank over a defined period of time while the vehicle is at a standstill after the engine controller has been switched off and comparing an expected pressure profile based on a given temperature profile based at least in part on the tank fill level and after the engine controller has been switched on to an actual measured pressure profile from a previous vehicle standstill phase. If the measured pressure profile lies within a settable tolerance around the expected pressure profile, the method confirms a leak-tight fuel tank. If the measured pressure profile lies outside the settable tolerance, the method identifies a faulty fuel tank and displaying an alert.

A method for diagnosing a purge line path of a tank ventilation system of a motor vehicle operated by an internal combustion engine is provided. The purge line path extends between a fuel vapor retention filter and an intake manifold of the motor vehicle, and includes a tank ventilation valve, a pressure sensor, a purge line path region arranged upstream of the pressure sensor, a purge line path region arranged downstream of the pressure sensor, a full load purge path arranged between the tank ventilation valve and the intake manifold, and a part load purge path arranged between the tank ventilation valve and the intake manifold. A plurality of part diagnoses are carried out temporally one after another for diagnosing the purge line path in the case of an active tank ventilation function, and pressure signals measured by the pressure sensor are evaluated within the context of the part diagnoses.

A vehicle, a vehicle fuel reactant leak detection system, a computer program product, and a computer implemented method of detecting leakage of a fuel reactant from a vehicle. The vehicle includes one or more fuel cell modules, a fuel supply source to supply a fuel reactant to the one or more fuel cell modules via a high-pressure fuel supply line, a fuel supply valve configured to open and close fuel reactant flow through the high-pressure fuel supply line, and a computing device, operatively connected to the fuel supply source. The computing device includes one or more processors caused to conduct, in response to a detection as sensor data of pressure in the high-pressure fuel supply line when the vehicle engine is in a non-operating state, fuel pressure analysis of the sensor data, and detect, based on the fuel pressure analysis, leakage of the fuel reactant at the fuel supply valve.

Methods and systems are provided for diagnostics and subsequent cleaning of an ejector in a fuel vapor purge system of a vehicle with a boosted internal combustion engine. In one example, a method may include, in response to indication of blockage in a fuel vapor purge system, a purge system valve may be actuated to a position enabling routing of contaminants blocking the ejector to an engine intake manifold, thereby cleaning the ejector.

In a fuel tank system, a control unit diagnoses a failure of a fuel storage unit and a processing unit. The fuel storage unit includes a vapor passage through which a fuel tank and a sealing valve are communicated with each other, a first pressure detection unit, and a second pressure detection unit disposed at a position different from the first pressure detection unit. The control unit specifies a presence or an absence of a clogging of the vapor passage based on 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 in the fuel tank is changed by the pressure generation unit in a condition that the sealing valve is controlled to be opened.