Fuel Injectors, Fuel Rails & Components

Fuel injectors are the components that spray fuel into the intake air stream in a fuel injection system. Unlike a carburetor that relies on pressure differential to atomize and draw fuel into the engine, fuel injectors spray and atomize fuel supplied by a high pressure pump. Today electronic multiport fuel injection is the most common injection type, but there have been several varieties, and the design and location of the injectors have varied accordingly.

Fuel injection began to replace carburetors in the 1970s. The mechanical Continuous Injection System (CIS) was an early variant found on European cars. In this system injectors mounted in the ports just ahead of the intake valves sprayed fuel continuously. The volume of fuel supplied to the injectors varied according to intake airflow. CIS evolved into the electronically controlled CIS-E, which managed fuel flow in response to inputs from various sensors.

Throttle Body Injection (TBI) was the first type of fuel injection used on many domestic cars and trucks in the 1980s, and was sort of a transition from carburetors to port injection. A TBI assembly is similar in size to a carburetor, mounts on an intake manifold and takes a similar air cleaner assembly. TBI is a self-contained fuel injection system with an integral fuel pressure regulator and one or two injectors mounted over the throttle plates. The injector contains a solenoid that, when energized by the PCM (Powertrain Control Module) moves a plunger that opens a valve, allowing fuel to spray from the injector nozzle.

Port fuel injectors are mounted in the intake manifold runners or cylinder head ahead of the intake valves. They are connected to the fuel rail, which is supplied with fuel from an electric fuel pump. A pressure regulator maintains a constant fuel pressure. In response to inputs from the oxygen sensor, mass airflow sensor, throttle position sensor, and other sensors, the PCM adjusts the pulse width, the length of time the injectors are open, so the amount of fuel injected can be tailored to engine load. In general, the pulse width is shorter at idle when less fuel is needed, and lengthened when the engine is under load and more fuel is needed.

Gasoline Direct Injection (GDI) is the latest form of fuel injection. Similar to a diesel engine, GDI injects fuel under extremely high pressure directly into the combustion chamber. GDI uses special quick response, high pressure fuel injectors, which allows the PCM to vary the timing of the injection event according to operating needs, and enables multiple injections. We offer new and remanufactured fuel injectors for all popular vehicles and fuel injection systems, as well as the necessary related components like fuel rails and the O-ring seals, which should be replaced whenever an injector is removed and installed.