As the main power unit of railway transportation, diesel locomotives are now developing towards high power, low fuel consumption and low exhaust emission. At the same time, people are more concerned about operation reliabilities and maintenance of diesel locomotives. It is well known that the operation processes of a fuel injection system (FIS) directly influence the power, exhaust emission, fuel economy and reliabilities of a diesel engine. The diesel engine can′t operate if the FIS breaks down. Because of the increase of injection pressure of the FIS and the use of poor quality fuel, more attention should be paid to the operation reliabilities of the FIS than ever before. So it is an urgent requirement to carry out some researches of the FIS fault diagnosis so as to maintain the diesel engine scientifically. To develop a fault diagnosis system of the FIS of diesel engines by analyzing high pressure fuel pipe (HPFP) pressure waveforms, FIS fault simulation experiments and computer simulations are carried out to study the characteristics of pipe pressure waveforms in detail. Data processing methods of the pipe pressure wave data and FIS fault diagnosis are also investigated. With the results of this thesis, many problems of the previous research work of FIS fault diagnosis carried out by other researchers are resolved effectively. The main contents are introduced as follows: As the main power unit of railway transportation, diesel locomotives are now developing towards high power, low fuel consumption and low emission emission. People are more concerned about operation reliabilities and maintenance of diesel locomotives. It is well known that the operation processes of a fuel injection system (FIS) directly affects the power, exhaust emission, fuel economy and reliabilities of a diesel engine. The diesel engine can not operate if the FIS breaks down. Because of the increase of injection pressure of the FIS and the use of poor quality fuel, more attention should be paid to the operation reliabilities of the FIS than ever before. So it is an urgent requirement to carry out the researches of the FIS fault diagnosis so as to maintain the diesel engine scientifically. develop a fault diagnosis system of the FIS of diesel engines by analyzing high pressure fuel pipe (HPFP) pressure waveforms, FIS fault simulation experiments and computers s imulations are carried out to study the characteristics of pipe pressure waveforms in detail. Data processing methods of the pipe pressure wave data in detail. carried out by other researchers are resolved effectively. The main contents are introduced as follows: