A fuel injector is a fuel metering device that sprays atomised droplets of fuel in a specific pattern into the engine’s intake manifold or directly into the combustion chamber. The injector has a solenoid and valve within, and the solenoid’s operation, or pulsing, is controlled by the powertrain control module (PCM). The PCM controls the solenoid’s “on” time to keep the air-fuel ratio optimised while the engine load and operating conditions constantly change. Fuel injectors are usually connected to a fuel rail located on the top of the engine, and the fuel rail, in turn, is supplied with fuel under pressure from the fuel pump located in the fuel tank.