A fuel level sensor detects the level of fuel in a fuel tank. A level signal detected by a float does not change in a full dead zone and an empty dead zone. During normal fuel consumption, the level signal changes according to the consumption amount. Thus when an electronic control unit, or ECU, detects that the fuel level sensor is operating normally, the ECU resets a fuel consumption amount. However, when a small quantity of fuel is supplied, the fuel consumption amount is not reset, and a measurement error may occur during failure detection. Accordingly, the ECU corrects a failure threshold value to avoid misdiagnosing a failure.

An engine control device includes: a pre-ignition determination module that determines whether an operation state of an engine indicated by a rotation speed detected by a rotation speed detection unit and a load calculated by a load calculating module is in a pre-ignition occurring region; a catalyst protection determination module that determines whether the operation state of the engine is in a catalyst protection region; and a fuel cut execution control module that stops a fuel supplied to the engine, when a remaining amount of a fuel tank is determined to be smaller than a tank threshold value and the operation state is determined to be in the pre-ignition occurring region, and when the remaining amount of the fuel tank is determined to be smaller than the tank threshold value and the operation state is determined to be in the catalyst protection region.

The present invention relates to a level indicator for determining the level of liquid in a container, the level indicator comprising: a floating device comprising a metal; a transmitter arranged to transmit an electromagnetic signal towards the floating device; and a receiver arranged to receive a response signal from the floating device. The floating device is moveable relative to the receiver so that a distance from the floating device to the receiver is altered in response to an altered level of liquid in the container, and wherein the electrical signal is a function of at least said distance. The receiver is electrically connectable to a control unit configurable to determine a position of the floating device relative to the receiver based on the electrical signal. The invention also relates to a system and a tank comprising the level indicator.

In one example in accordance with the present disclosure, a method is described. According to the method, an actual volume of fuel added to at least one fuel tank is determined. It is also determined, an amount of fuel indicated as having been added to the fuel tank from a refueling station. The actual volume added is compared to the amount of fuel indicated as having been added to determine a difference between the two values.

The measured volume of fuel in a storage tank of a vehicle is determined by positioning a sensor within a storage tank holding the fuel. A processor is also located on the vehicle for receiving data relative to the volume of the fuel in the storage tank, the mileage of the vehicle, and vehicle location, date, and time, for transmitting such data to a remote or centralized server (“RS”). The RS also receives fuel dispensed data from a fuel dispensing station (“FDS”), including location, date/time, and volume of fuel dispensed to the storage tank of the vehicle. The RS then compares the data received from the vehicle processor with the fuel dispensed data to determine whether there are any discrepancies between the dispensed volume of fuel purchased, as indicated in the FDS data, and the measured increase of volume of fuel in the vehicle at the time of dispensing from the FDS.

A method can include emitting, from a light source, directional light through fuel contained in a fuel tank, and determining a refraction angle of the directional light after the directional light passes through an interface with the fuel. The method can further include determining, by a processing device, an index of refraction of the fuel based on the determined refraction angle, and determining, by the processing device, a density of the fuel based on the determined index of refraction of the fuel.

An indicator disposed proximate a fuel port of the vehicle is disclosed. The indicator comprises a persistent luminescent layer, a first light source, and one or more circuits. The persistent luminescent layer is configured to emit a first color of light. The first light source is configured to emit a charging emission to charge the persistent luminescent layer. The one or more circuits are configured to selectively activate one or more portions of the first light source such that the persistent luminescent layer is charged and illuminates the indicator in the first color.

Methods and systems are presented for diagnosing operation of passive grade vent valves of a fuel system. The methods and systems include adjusting a position of a vehicle so that fuel in a fuel tank may cause a first grade vent valve to open and a second grade vent valve to close.

Methods and systems are provided for conducting an engine off natural vacuum test in a vehicle in order to indicate the presence or absence of undesired evaporative emissions. In one example, a vehicle fuel system and evaporative emissions system are sealed from atmosphere, and responsive to a pressure increase below an expected threshold, the fuel system and evaporative emissions system are actively pressurized via circulating hot engine coolant to a heater core and blowing hot air through the vehicle cabin to the fuel system via a three way ventilation valve in the rear of the vehicle. In this way, false failures of EONV test procedures due to environmental factors and vehicle operator drive habits may be reduced, and unnecessary engine service may be avoided.

A method, comprising indicating an amount of a residual fuel in a fuel tank based on an initial rate of change of a fuel tank pressure during a refueling event. The initial rate of change of fuel tank pressure is proportionate to the amount of vapor dome space within the fuel tank, and thus proportionate to the amount of residual fuel left in the fuel tank. In this way, the fuel tank fill level may be accurately quantified, even during cases where the fill level indicator experiences degradation.