FUEL INJECTION: Now let's discuss how a fuel injection system operates. As the diagram shows, in a fuel injection system, gas is pulled from the fuel tank by the electronic fuel pump and it is delivered under pressure to the injectors. From there the fuel injection control unit meters the injection of the fuel to the combustion chambers. As this is happening, air is also being drawn through the air intake manifold and the air and fuel are only mixed in the combustion chambers. The control unit utilizes sensors to monitor the air, fuel and exhaust functions while the pressure regulator makes sure the fuel pressure stays at a constant rate. Some systems utilize a fuel distributor to distribute the fuel from the fuel pump to each injector. Also, some systems make use of a cold start injector valve which acts as a choke to start the engine when it's cold. Injection in model carburetor systems have a hook-up device which plugs into a computer which helps your mechanic pinpoint problems with the sensors, control unit, compression, timing, and emissions as well as other functions in your car. A throttle body or a port injection system utilizes a carburetor like throttle body that mixes the air and fuel together before sending it to the intake manifold and combustion chamber via a single injector. Maintenance of the fuel injection system involves periodically changing the air filter and especially the fuel filter at the recommended intervals.
