A fuel injection system for an internal combustion engine, comprising: - a first fuel source for providing fuel of a relatively high pressure; - a return channel connected to a second fuel source for accommodating fuel of relatively low pressure in relation to the pressure of the fuel provided from the first fuel source ; - a residual pressure regulator comprising an inlet and an outlet , which outlet is connected to the return channel ; - a fuel injector comprising an inlet channel connected to the first fuel source , a control valve arrangement comprising an inlet, an outlet and a return port , whereby the inlet of the control valve arrangement is connected to the inlet channel and the outlet of the control valve arrangement is connected to an outlet channel , wherein the fuel injector further comprises a fuel injection nozzle comprising an outlet chamber connected to the outlet channel , an injection outlet connected to the outlet chamber and a needle member , wherein the needle member is at least partially provided in the outlet chamber and biased at least partially by a biasing member to a nozzle closed position whereby fluid communication between the outlet chamber and the injection outlet is blocked, and wherein the fuel injection nozzle is configured such that the needle member is biased to open fluid communication between the outlet chamber and the injection outlet by a pressure in the outlet chamber ; and wherein the fuel injection system further comprises: - a spill valve provided between the outlet channel and the return channel , wherein the residual pressure regulator is connected by its inlet to the spill valve and configured to regulate pressure at its inlet to a residual pressure that is higher than the pressure in the return channel but lower than the pressure of the first fuel source , characterized in that further the return port is connected to the return channel downstream the residual pressure regulator . - a first fuel source for providing fuel of a relatively high pressure; - a return channel connected to a second fuel source for accommodating fuel of relatively low pressure in relation to the pressure of the fuel provided from the first fuel source ; - a residual pressure regulator comprising an inlet and an outlet , which outlet is connected to the return channel ; - a fuel injector comprising an inlet channel connected to the first fuel source , a control valve arrangement comprising an inlet, an outlet and a return port , whereby the inlet of the control valve arrangement is connected to the inlet channel and the outlet of the control valve arrangement is connected to an outlet channel , wherein the fuel injector further comprises a fuel injection nozzle comprising an outlet chamber connected to the outlet channel , an injection outlet connected to the outlet chamber and a needle member , wherein the needle member is at least partially provided in the outlet chamber and biased at least partially by a biasing member to a nozzle closed position whereby fluid communication between the outlet chamber and the injection outlet is blocked, and wherein the fuel injection nozzle is configured such that the needle member is biased to open fluid communication between the outlet chamber and the injection outlet by a pressure in the outlet chamber ; and - a spill valve provided between the outlet channel and the return channel , wherein the residual pressure regulator is connected by its inlet to the spill valve and configured to regulate pressure at its inlet to a residual pressure that is higher than the pressure in the return channel but lower than the pressure of the first fuel source , characterized in that further the return port is connected to the return channel downstream the residual pressure regulator . <EOS>