This section examines basic EFI systems. EFI systems use electronically controlled injectors to spray the fuel. There are two basic systems. Throttle body injection, also called single point injection. And multi point injection. Throttle body injection sprays fuel into the air as it passes through to the fuel. And as it passes through to the intake manifold. Multi point injection has an injector for each cylinder, which sprays fuel directly into the intake valve port. The whole system has a fuel tank to store the fuel. A fuel pump to circulate fuel and provide pressure in the system. A fuel filter to clean the fuel and protect the injectors. A fuel rail or pipe to supply the injectors with fuel. Injectors which spray into the intake valve ports. A pressure regulator to control pressure in the system. A throttle body with a throttle valve to control the flow of air to the engine. An air cleaner ducting and an air flow meter to provide clean measure air. And a plenum chamber or surge chamber to dampen the flow of air. There is also an electronic controlled unit, a computer that receives data from sensors around the engine. It processes this data and uses the results to operate the injectors. The system is a very important tool for the injectors. It is a very important tool for the injectors. It is a very important tool for the injectors. It is a very important tool for the injectors. It is a very important tool for the injectors.