A fuel injection system is disclosed for an internal combustion engine that has multiple combustion chambers and a camshaft which cyclically imparts pressurization energy to and recovers pressurization energy from fuel being supplied to the engine. The fuel injection system includes a plurality of unit injectors, a camshaft linkage which simultaneously reciprocates pressurizing plungers of a set of at least two unit injectors and an interconnecting line which allows selective fluid interconnection between fuel pressurization chambers formed within the unit injectors. The interconnection line allows fluid linkage of the volume of fuel which is simultaneously pressurized and depressurized within the interconnected fuel pressurization chambers of a first set of unit injectors.