A. Fault possible cause and fault treatment (gas): (1). Gas cylinder has no gas or hand valve of gas cylinder is not open. Fault treatment: add gas or turn on hand valve of gas cylinder. (2). High pressure solenoid valve has no electricity or is damaged. Fault treatment: turn on the ignition key and then the solenoid valve has ringing “thump” sound. The connector clip of high pressure solenoid valve shall be plugged tightly. If the solenoid valve is damaged, please replace it. (3). Low pressure solenoid valve on FMV cannot be open or is not open fully. Fault treatment: inspect with notebook computer. After the ignition key is turned on, the gas pressure value is lower than 110PSIA. Please replace the solenoid valve or inspect valve plug. (4). Gas pressure is low. Fault treatment: inspect whether gas pipeline leaks gas. B. Fault possible cause and fault treatment (ignition circuit) : (1). Two relays of engine control module are damaged, therefore, please inspect whether three supply lines have electricity. Fault treatment: turn on the ignition key and inspect whether relay and fuse have 24V voltage with multimeter according to electrical diagrams. (2). Ignition module is damaged. Fault treatment: detect that the inanition coil misfires. Please inspect fault code, spark plug and high-tension cable. (3). Start-up rotary speed is too low (the lowest start-up rotary speed is 100r/min) Fault treatment: inspect whether the battery voltage can reach 24V. (4). Engine control module (ECM) is damaged. Fault treatment: replace ECM. C. Fault possible cause and fault treatment (air gas circuit and others): (1). Air intake is not sufficient Fault treatment: inspect whether air filter and air intake system are blocked and leaked. (2). Oxygen sensor connector clip is fused and short circuit is caused. Fault treatment: replace oxygen sensor. (3). Electronic throttle valve is damaged. Fault treatment: use software to test electronic throttle valve. If the electronic throttle valve is damaged, please replace it. (4). Intake valve and exhaust valve are adjusted wrongly. Fault treatment: inspect valve clearance according to instruction manual of diesel engine. (5). Some circuits on the finished vehicle have problems, such as neutral gear switch and etc. Fault treatment: inspect the circuits of the finished vehicle. (6). Velocity sensor fault. Fault treatment: use software to detect and then there is a fault code. Inspect the clearance between fluted disc and sensor. (7). The gear cup of signal generator turns and the angle of ignition advance changes greatly. At this moment, signal generator is fractured. Fault treatment: adjust the position of gear cup to make TDC scale mark aligning at central position inclining to the engine of speed sensor. Please carefully inspect whether the signal generator is fractured. If yes, please replace signal generator assembly.