An engine is a machine that can convert other forms of energy into mechanical energy, including, for example, an internal combustion engine (gasoline engine, etc.), an external combustion engine (Stirling engine, steam engine, etc.), an electric motor, and the like. For example, internal combustion engines usually convert chemical energy into mechanical energy. There are many cases happen to engine, for wonepart we have experience of engine repair and rebuild projects, if your engine have the following problems, then you will check the following reasons as reference: 1. When the start switch is engaged, the engine crankshaft will not rotate Possible reason • Battery output is too low • Defective wire or switch • The electromagnetic switch of the starting motor is faulty • The starting motor is faulty • Intrinsic problems affecting the rotation of the engine crankshaft 2. Start the motor crank, but the engine cannot start Possible reason • No fuel in the fuel tank • Poor fuel quality • The fuel filter is dirty • The fuel pipe is dirty or damaged • Low fuel pressure • There is air in the fuel system • The fuel system and engine are not at the correct timing • The exhaust valve is always open (the fuel does not have high enough pressure to start the engine) • Turning speed is too low • No fuel in the fuel injection pump housing