A fuel system evaluation method was introduced to select the proper high pressure injection system for diesel engines. Using this method, the second generation common rail system of BOSCH Company was selected for use in the 4JB1 diesel engine. Based on this common rail system, a fuel supplying model was built using AMESim. The model included a high pressure pump submodule, a pressure control valve submodule, an injectors submodule, and a connecting pipes submodule. Through model simulation, the influences of parameters (e.g., rail volume, high pressure pipe length and diameter) on pressure fluctuations and pressure building were studied. Railpipe system parameters were selected based on simulation results. Experimental results show the railpipe parameters could satisfy the needs of rapid pressure response and low pressure fluctuations for common rail diesel engines.