If the pressure in a supply passage drops at a speed greater than a first determination speed in a state in which a first mode for supplying gas fuel to an internal combustion engine is selected, a control apparatus inhibits selection of the first mode. Then, the control apparatus switches from the first mode to a second mode, in energy other than gas fuel is used. In this state, if the pressure in the supply passage drops at a speed greater than a second determination speed, the control apparatus maintains the state in which the second mode is selected. If the pressure in the supply passage drops at a speed lower than the second determination speed, the control apparatus cancels the inhibition of selection of the first mode when it is detected that a manual on-off valve is opened.

The disclosure relates to a method for determining a size of a leak in a fuel tank system. The method includes: starting an internal combustion engine; calculating a stoppage time for a vehicle and/or a temperature difference between the fuel in the fuel tank system and the environment; and checking whether at least one of a plurality of diagnostic conditions is fulfilled. A first diagnostic condition is fulfilled when the stoppage time is longer than a predetermined minimum stoppage time. A second diagnostic condition is fulfilled when the temperature difference is smaller than a predetermined maximum temperature difference. Additionally, when at least one of the plurality of diagnostic conditions is fulfilled, the method includes: evacuating the fuel tank system; recording a time profile of the pressure in the fuel tank system; and determining the size of a leak based on the recorded time profile of the pressure.

Methods and systems are provided for operating a fuel system configured to deliver a gaseous fuel to an engine. While the engine is shutdown, diagnostic routines may be performed to identify fuel system leaks or breaches. When the engine is subsequently restarted, fuel rail pre-priming is adjusted based on the presence of fuel system leaks.

An apparatus and method for controlling a fuel injection system of an internal combustion engine is disclosed. Each fuel injector in the system is operated to perform a predetermined injection pattern per engine cycle. A signal representative of a fuel pressure within the fuel rail during the operation of the fuel injectors is sampled. A Fourier analysis of the fuel rail pressure signal is performed to determine one or more harmonic components thereof. The determined harmonic components of the fuel rail pressure signal are used to calculate a dynamic fuel quantity that flows through a fuel injector during an injection pulse of the injection pattern. A fuel quantity actually injected by the fuel injector during the injection pulse as a function of the dynamic fuel quantity is calculated.

A method is disclosed of controlling operation of a fuel injector in response to measuring a quantity of fuel injected by the fuel injector from a fuel accumulator to an engine cylinder during operation of a fuel pump that delivers fuel to the accumulator, comprising: determining an average pressure of the fuel accumulator during a first time period before a fuel injection event; predicting a mass of fuel delivered to the fuel accumulator during a pumping event (Q.sub.pump); determining an average pressure of the fuel accumulator during a second time period after the fuel injection event; estimating a leakage of fuel; computing the injected fuel quantity by adding the average pressure during the first time period to Q.sub.pump, and subtracting the average pressure during the second time period and the leakage; and using the computed injected fuel quantity to control operation of the fuel injector.

A method for operating an internal combustion engine with a high pressure accumulator for a fuel injection system, includes the steps of: monitoring, in a time-dependent manner, a high pressure in the fuel injection system; conducting a check, at a high pressure-dependent starting time point, as to whether a continuous injection detection is to be carried out; and checking whether a high-pressure oscillation has occurred within an oscillation time interval prior to a starting time.

A method and system of testing a tightness of a closed container using a two-part test. The first part of the two-part test includes connecting the closed container to a gas supply and filing the closed container with a testing gas from the gas supply. A first leak rate of the closed container is measured over a first period of time, and when the first leak rate is less than a first threshold, the controller identifies the closed container as compliant. Conversely, when the first leak rate is greater than the first threshold, the controller measures a second leak rate of the closed container over a second period of time. When the second leak rate is greater than a second threshold, the controller identifies the closed container as noncompliant, and when the second leak rate is less than the second threshold, the controller identifies the closed container as compliant.

A method of adaptively predicting, during operation of a pump, a mass of fuel pumped by the pump during a pumping event to a fuel accumulator (“Q.sub.pump”) to control operation of the pump is provided, comprising: generating an adaptive model of operation of the pump, including estimating a start of pumping (“SOP”) position of a plunger of the pump, estimating Q.sub.pump, determining a converged value of the estimated SOP position, and determining a converged value of the estimated Q.sub.pump; using the adaptive model to predict Q.sub.pump by inputting to the model the converged value of the estimated SOP position, a measured pressure of fuel in the fuel accumulator and a measured temperature of fuel in the fuel accumulator; and controlling operation of the pump in response to the predicted Q.sub.pump.

A control device transmits an opening degree command amount to an actuator to command an opening degree of a sealing valve. The control device sets a pressure difference between a tank-side pressure and a canister-side pressure to a specified value or more. The control device causes a pressure variable device to change the canister-side pressure to form a state in which the pressure difference becomes equal to or higher than a specified value while the sealing valve is closed. The control device learns a valve opening start amount based on the opening degree command amount when the tank-side pressure changes in response to the opening degree command amount that gradually increases from zero. The control device determines the opening degree command amount based on the valve opening start amount, which has been learned.

A method for operating an injection system of an internal combustion engine, including: providing the injection system includes a high pressure accumulator; regulating a high pressure in the high pressure accumulator in a normal operation by way actuating a low pressure-side suction throttle; regulating the high pressure in a first operating mode of safety operation by way of actuating at least one high pressure-side pressure control valve; carrying out a switchover from the normal operation into the first operating mode of safety operation if the high pressure reaches or exceeds a first limit pressure value; and carrying out a switchover from the first operating mode of safety operation into the normal operation if, starting from above a setpoint pressure value, the high pressure reaches or undershoots the setpoint pressure value, which is lower than the first limit pressure value.