A fuel supply device for supplying fuel into a combustion chamber of an internal combustion engine is provided. The device includes: a low pressure fuel supply pipe to which a low pressure fuel is supplied; a high pressure fuel supply pipe to which high pressure fuel to be supplied into the combustion chamber is supplied; fuel supply units provided between the low pressure fuel supply pipe and the high pressure fuel supply pipe, each of the fuel supply units being configured to boost the fuel in the low pressure fuel supply pipe and supply the boosted fuel to the high pressure fuel supply pipe; and a control unit configured to control the fuel supply units. The control unit controls the fuel supply units such that a total amount of ejection of the fuel ejected from the fuel supply units per unit time is close to a constant value.

A fuel supply device for supplying fuel into a combustion chamber of an internal combustion engine is provided. The device includes: a low pressure fuel supply pipe to which a low pressure fuel is supplied; a high pressure fuel supply pipe to which high pressure fuel to be supplied into the combustion chamber is supplied; fuel supply units provided between the low pressure fuel supply pipe and the high pressure fuel supply pipe, each of the fuel supply units being configured to boost the fuel in the low pressure fuel supply pipe and supply the boosted fuel to the high pressure fuel supply pipe; and a control unit configured to control the fuel supply units. The control unit controls the fuel supply units such that a total amount of ejection of the fuel ejected from the fuel supply units per unit time is close to a constant value.

In a high pressure pump in a system for fuel injection in a combustion engine, determining whether a predetermined partial load operating condition prevails in the combustion engine, at which one single of several pump elements (10) in the high pressure pump is capable of alone delivering a fuel pressure requested in an accumulator tank (6), according to a first reference value, and to achieve a reproducible increase of the fuel pressure to a second reference value. If applicable, the high pressure pump's pump elements are controlled so that one single pump element alone delivers the fuel pressure in the accumulator tank according to the first reference value, whereupon this reference value is changed to the second reference value, and the actual development of the pressure in the accumulator tank as a function of time is determined, and compared with stored values of similar developments for the determination of information regarding the pump element's performance ability.