Disclosed is a method for estimating an angular position of top dead center for a high-pressure fuel injection pump that forms part of a system for injecting fuel into a motor vehicle engine, the pump including at least one piston moving in a chamber between the top and the bottom dead center, the pump being equipped with a digital control valve for controlling a quantity of fuel, an electrical current being applied to the digital valve as it closes then removed in order to open the digital valve, a movement of the digital valve in the direction of opening creating an induced current which makes it possible to detect a position of start-of-opening of the digital valve. An instant at which the pump piston passes through top dead center is estimated as a function of an instant at which the position of start-of-opening of the digital valve appears.

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.

Methods and systems are provided for enforcing a minimum fuel lift pump commanded voltage that is determined as a function of commanded lift pump pressure and fuel flow rate. The minimum fuel lift pump voltage is applied when the commanded voltage is lower than the minimum voltage. The approach reduces engine stalls induced by ingestion of fuel vapors at an injection pump coupled downstream of the lift pump.

Methods and systems are described for a fuel system in an engine comprising two lift pumps. One example method comprises deactivating one of a first lift pump and a second lift pump if fuel fill level in a common reservoir decreases below a threshold fill level, wherein the first lift pump and the second lift pump are positioned in the common reservoir. By deactivating one of the two lift pumps, the two lift pumps may be protected from degradation due to fuel starvation.

The present invention relates to a fuel system for a combustion engine, the fuel system comprising a low-pressure circuit comprising at least one fuel tank, at least one low-pressure fuel pump, a first fuel filter and a second fuel filter which is arranged downstream of the first fuel pump, and a high-pressure circuit comprising a high-pressure fuel pump. The high-pressure fuel pump comprises means to suck fuel from the low-pressure circuit and in case of failure in the at least one low-pressure fuel pump, to suck fuel from the low-pressure circuit and the fuel is arranged to by-pass the at least one low-pressure fuel pump and optionally, at least one of the first or second fuel filters, via at least one by-pass pipe comprising a check valve that prevents the flow of fuel back to the fuel tank.

A vehicle propulsion system includes a first pump having an inlet for receiving fuel from a fuel reservoir and an outlet for providing pressurized fuel to a fuel feed line at a first pressure, a fuel feed line pressure sensor, a second pump having an inlet for receiving fuel from the fuel feed line and an outlet for providing pressurized fuel to an engine fuel rail at a second pressure, the second pressure being higher than the first pressure, a fuel temperature sensor, and a controller controlling the first pump to reduce the pressure of the fuel in the fuel feed line and determining whether the pressure of the fuel in the fuel feed line has reached a vaporization pressure of a component in the fuel.

A method and a system for control of a low-pressure circuit in a fuel system of a vehicle, which circuit is arranged to provide the vehicle's engine with fuel from at least one fuel tank via a pressure change system. The system includes a determination unit to make a determination of a future working point for the engine. The determination unit bases this determination on information about a section of road ahead. The system also has a pump operating unit which operates at least one controllable fuel pump which is part of the low-pressure circuit. The pump operating unit bases this operation on the future working point.

A method of preventing an engine stall of a vehicle having a fuel injection device for pressurizing fuel stored in a fuel tank by a high-pressure fuel pump to transmit the fuel to a common rail, and injecting the fuel temporarily stored in the common rail into an engine through an injector may include steps of determining whether or not a drift occurs in an output signal of a high-pressure fuel pressure sensor for measuring fuel pressure at a downstream side of the high-pressure fuel pump, and performing a fuel pressure control by replacing a high-pressure fuel pressure value with a predetermined pressure value based on the output signal of the high-pressure fuel pressure sensor.

Methods and systems are provided for an engine to infer fuel temperature from a measured rate of change in a pressure of a fuel passage between a low pressure fuel pump and a high pressure fuel pump during certain operating conditions, including when the low pressure fuel pump is switched off. The operation of the low pressure fuel pump may be adjusted responsively to a change in the inferred fuel temperature.

Embodiments of a gaseous or dual fuel electronic pressure regulation system (EPRS) for a multipoint fuel injection engine are described herein. Additionally, embodiments of a method for controlling the EPRS are provided. In particular, the EPRS employs an electronic pressure regulator (EPR) capable of accurately determining and controlling the mass flow of gaseous fuel into a fuel rail so as to avoid pressure droop and over- and under-pressurization of the gas admission valves (GAVs). By using the EPRS described above, mass flow is able to be distributed to the downstream manifold or engine cylinders very accurately, and the GAVs are able to be driven simultaneously in a pressure/pulse duration that is optimal for accurate and repeatable operation.