Throttle Body Injection:Older injection systems used TBI (Throttle Body Injection) which electronic fuel injectors build inside. This technology has since been advanced for better fuel economy with the now common multiport fuel injection system.Fuel Injection:The Fuel injection system is more efficient and drastically reduces emissions. Intake manifold shares one common fuel rail for all cylinders which feed fuel into injectors (located in the intake runners near the combustion chamber). The air comes in through the throttle body port on the intake manifold. The vehicle’s computer sends a signal to the injectors and tells them when to open and for how long to stay open.Electronic Fuel Injection;The aftermarket industry has created a ‘stand-alone system, which is a combination of the throttle body & fuel injections, that doesn’t require a separate computer to control it. It can bolt right in place of your carburetor, it is self-tuning and will lower emissions. Having its own built-in computer makes for an easy swap.Electronic fuel injection systems require more fuel pressure than a carburetor. A mechanical fuel pump will be inefficient, instead, an electric fuel pump is required.
Diesel Fuel Systems (common rail);
Fuel starts off in the fuel tank, where it is pulled up by an electric pump (this pump does not increase pressure—it’s designed as a ‘volume pump’). The fuel is sent into the fuel filter which removes any unwanted contamination or debris from the fuel before it is sent further on its way through the system. The fuel then travels to an electronic fuel pump that increases volume and pressure. The fuel is then sent onto a mechanical high-pressure fuel pump, this pump is timed as it is driven by the timing belt.
Note- As the fuel makes its way through the system, the pressure is increased. At this point, the fuel traveling through rubber lines to a hard material line.
The fuel now reaches the fuel rail that includes a pressure sensor. The high-pressure fuel enters at one end of the rail and is distributed out to each of the fuel injectors. These injectors directly inject the high-pressure fuel into the cylinder, creating the necessary power for the vehicle.
Note– There is also a low-pressure line that runs between the injectors and acts as a control side. Without this low-pressure control side, the injectors won’t work.