A FUEL INJECTION SYSTEM

A fuel injection system includes a first high pressure fuel source, a return channel connected to a second low pressure fuel source, a residual pressure regulator having an inlet and an outlet connected to the return channel, and a fuel injector having a control valve arrangement comprising an inlet, an outlet and a return port, a fuel injection nozzle having an outlet chamber, an injection outlet, and a needle member in the outlet chamber. The needle member is biased to a closed position to block fluid communication between the outlet chamber and the injection outlet, and to open fluid communication by a pressure in the outlet chamber. The residual pressure regulator is connected to a spill valve to regulate pressure to a residual pressure higher than the pressure in the return channel and lower than the pressure of the first fuel source.