1, identify the cause of the failure. For the failure of engine to start such a fault, the battery should first be detected. It is necessary to make sure that the battery is not enough if the engine fails to start. 2. Detection of ignition timing. The slip phenomenon of the timing belt is the fundamental reason for the failure of the spark and the failure of the engine to start. 3. Test the starting system. For the engine to fail to start such a failure, the first thing to do is to detect the circuit in the engine starting system. From the most basic form, the circuit of the starting system generally includes the most basic parts, that is, the battery, the starting motor, and the cables that connect the components. Of course, in addition to this, ignition switches, start - up relays or electromagnetic coils, as well as car - borne anti-theft systems, are also an important part of the startup system. 4. Test the quality of electric spark. When the circuit of the start-up system is tested and proved that there is no fault, it should focus on why the engine can not work. Generally speaking, the first test is the ignition system of the engine, which is also the simplest test. In the early ignition system, you can easily take off the ignition coil, and then use an EDM detector to check whether the spark is normal. When selecting a spark detector, a adjustable detector is preferable to a fixed design, because it allows you to adjust the detector to a smaller gap, so you can know, is there no spark at all, or a spark but very weak? 5, test the fuel system. The diagnosis of fuel system can be divided into two parts: diagnosis of fuel supply system and diagnosis of injector circuit system. The fuel supply system can be detected by measuring the flow and pressure of fuel. The best way to measure fuel flow is to detect pipelines in the fuel supply line with load. 6, detection of anti-theft system: vehicle anti-theft system will also produce some often ignored fuel supply system failure. Some car manufacturers include parameter identification in data flow of anti-theft system. On many vehicles, replacing the modules of the anti-theft system without initializing them properly will cause the car to fail to start. In some specific cases, for example, when a master key is missing, it is necessary to replace the multi-function controller to enable the engine to start normally.