A fuel supply device for a liquefied petroleum direct injection (LPDI) engine in which liquefied petroleum gas (LPG) is directly injected into a combustion chamber and a start control method of an LPDI engine having the fuel supply device, wherein the high pressure fuel pump receives and compresses fuel to a pressure higher than a pressure at which fuel has been supplied, wherein the high pressure fuel rail buffers and supplies fuel to a direct injector that injects fuel directly into a combustion chamber, wherein the return line is connected to the supply line through the high pressure fuel pump to form a low pressure line, allowing a surplus portion of fuel supplied to the high pressure fuel pump from the fuel tank to return to the fuel tank, and wherein a first valve is disposed on the return line to control the flow rate of returning fuel.

A method of operating a cryogenic fuel system for supplying fuel to an engine is provided herein. A cryogenic fuel pump is operated to pump fuel to be supplied to the engine. At least a portion of the pumped fuel is diverted to be supplied to an accumulator, when a fuel demand of the engine is less than a discharge output of the cryogenic fuel pump. Further, the supply of the pumped fuel from the cryogenic fuel pump to the engine and the accumulator is stopped, when a pressure within the accumulator reaches a first predefined pressure limit. Furthermore, the fuel is supplied to the engine from the accumulator, when supply of the pumped fuel from the cryogenic fuel pump to the engine and the accumulator is stopped.

The invention relates to a method for operating a fuel supply pump of a vehicle, the vehicle comprising a combustion engine system and a gearbox, the method comprising the steps of: determining one or more operational values of at least one operational parameter of the combustion engine system; determining a reduction of a fuel provision rate to the combustion engine system; determining whether a gear step change of the gearbox is at hand, on the basis of the determined one or more operational values of the at least one operational parameter; and in case a gear step change of the gearbox is at hand, controlling operation of the fuel supply pump so as to maintain fuel supply pump speed.

The invention relates to a method for operating a fuel supply pump of a vehicle, the vehicle comprising a combustion engine system and a gearbox, the method comprising the steps of: determining one or more operational values of at least one operational parameter of the combustion engine system; determining a reduction of a fuel provision rate to the combustion engine system; determining whether a gear step change of the gearbox is at hand, on the basis of the determined one or more operational values of the at least one operational parameter; and in case a gear step change of the gearbox is at hand, controlling operation of the fuel supply pump so as to maintain fuel supply pump speed.

A fuel supply system includes an electronic control unit that outputs a target fuel pressure for controlling a low-pressure pump and an engine status, and a fuel pump controller (FPC) that generates a drive signal for driving the low-pressure pump based on the target fuel pressure. The FPC is configured to obtain an actual fuel pressure, to set a duty ratio and to perform a feedback control for the actual fuel pressure to follow the target fuel pressure, and to set a lower limit guard value based on the engine status. The lower limit guard setter sets a duty ratio of 0% as the lower limit guard value when the engine status indicates a stop of the engine.

Systems and methods are provided for operating a port fuel and direct injection fuel system of a rolling variable displacement engine (rVDE). In one example, a method may include selecting between controlling a lift pump of the fuel system to output fuel at a mechanically limited pressure and controlling the lift pump to output fuel at a pressure lower than the mechanically limited pressure based on whether port fuel injection is used. In this way, the lift pump may be controlled without feedback from a pressure sensor, reducing system costs, while electrical power consumption increases due to operating the lift pump to output fuel at the mechanically limited pressure are minimized due to the rVDE technology, which reduces port fuel injection usage.

A vehicle includes a residual pressure holding valve provided downstream a feed pump of a fuel to hold a pressure in a fuel pipe leading to the port injection valve. Residual pressure holding valve is opened to return the fuel in the fuel pipe to the fuel tank when the pressure in the fuel pipe exceeds a valve opening pressure, and closed when the pressure in the fuel pipe is lower than the valve opening pressure. At the time of a request to reduce a target pressure of the fuel to be supplied to the electric feed pump, a control device refrains from causing the target pressure to decrease when a load of the engine is smaller than a prescribed value, and causes the target pressure to decrease when the load of the engine is greater than the prescribed value.

Methods and systems are provided for operating a fuel system comprising two lift pumps. In one example, a method may comprise adjusting operation of a first lift pump to achieve a desired fuel rail pressure. The method may comprise powering on a second lift pump to achieve the desired fuel rail pressure when operating only the first lift pump is not sufficient to achieve the desired fuel rail pressure.

A fuel pressure sensor diagnosis device includes an electronic control unit configured to drive a fuel supply device during electric traveling of a hybrid vehicle, to perform determination as to whether an output of a fuel pressure sensor is within a normal range after driving of the fuel supply device is started, and to perform a diagnosis to determine whether a malfunction has occurred in the fuel pressure sensor based on a result of the determination, the normal range being an assumed range of the output of the fuel pressure sensor in a case where the fuel pressure sensor normally functions and the fuel supply pressure is a prescribed upper limit pressure.

Systems and methods are provided herein for tracking degradation of a high-pressure fuel pump. In one example, a fuel system controller is configured to receive an output pressure signal from a pressure sensor, transform the output pressure signal to the frequency domain to generate frequency content of the output pressure signal, and diagnose a condition of a fuel pump based at least in part on the frequency content of the output pressure signal, the fuel pump fluidly coupled to a fuel injector via a common fuel rail, and the fuel injector is operable to inject fuel to a cylinder of an engine.