A fuel injection system of an internal combustion engine, comprising: - an injector having a hydraulic control chamber controlling the delivery of fuel through the injector, - an actively controlled first valve system controlling the pressure relief from the control chamber, the first valve system being movable between: - a first position in which the first valve system closes the injector by deterring the pressure from being relieved from the control chamber through a first relief circuit, and - a second position in which the first valve system opens the injector by allowing the pressure to be relieved from the control chamber through the first relief circuit, the control chamber being connected to the first valve system through a first relief line for relieving fuel from the control chamber through the first valve system, the fuel injection system comprising a second relief circuit allowing the pressure to be relieved from the control chamber, wherein the fuel injection system includes a needle and a pressure in the control chamber controls the position of the needle and the delivery of fuel through nozzles; characterized in that the second relief circuit comprises a second valve system, having a control port (32.3) passively controlled by the fuel pressure in a passive control line connected to the first valve system through an opening control line, the opening control line being distinct from the first relief line, and the second valve system being movable between: - when pressure (Pj) in the passive control line is above a first pressure threshold, a first position in which the second valve system deters the pressure from being relieved from the control chamber through the second relief circuit and - when pressure (Pj) in the passive control line is under the first pressure threshold, a second position in which the second valve system allows the pressure to be relieved from the control chamber through the second relief circuit. - an injector having a hydraulic control chamber controlling the delivery of fuel through the injector, - an actively controlled first valve system controlling the pressure relief from the control chamber, the first valve system being movable between: - a first position in which the first valve system closes the injector by deterring the pressure from being relieved from the control chamber through a first relief circuit, and - a second position in which the first valve system opens the injector by allowing the pressure to be relieved from the control chamber through the first relief circuit, - a first position in which the first valve system closes the injector by deterring the pressure from being relieved from the control chamber through a first relief circuit, and - a second position in which the first valve system opens the injector by allowing the pressure to be relieved from the control chamber through the first relief circuit, - when pressure (Pj) in the passive control line is above a first pressure threshold, a first position in which the second valve system deters the pressure from being relieved from the control chamber through the second relief circuit and - when pressure (Pj) in the passive control line is under the first pressure threshold, a second position in which the second valve system allows the pressure to be relieved from the control chamber through the second relief circuit.