How Fuel Injection Systems Work
In trying to keep up with emissions and fuel efficiency laws, the fuel system used in modern cars has changed a lot over the years. The 1990 Subaru Justy was the last car sold in the United States to have a carburetor; the following model year, the Justy had fuel injection. But fuel injection has been around since the 1950s, and electronic fuel injection
was used widely on European cars starting around 1980. Now, all cars sold in the United States have fuel injection systems.
In this article, we'll learn how the fuel gets into the cylinder of the engi-ne, and what terms like "multi-port fuel injection" and "throttle body fuel injection" mean.
-For most of the existence of the internal combustion engine, the carburetor has been the device that supplied fuel to the engine. On many other machines, such as lawnmowers and chainsaws, it still is. But as the automobile evolved, the carburetor got more and more complicated trying to handle all of the operating requirements. For instance, to handle some of these tasks, carburetors had five different circuits:
Main circuit - Provides just enough fuel for fuel-efficient cruising
Idle circuit - Provides just enough fuel to keep the engine idling
Accelerator pump - Provides an extra burst of fuel when the accelerator pedal is first depressed, reducing hesitation before the engine speeds up
Power enrichment circuit - Provides extra fuel when the car is going up a hill or towing a trailer
Choke - Provides extra fuel when the engine is cold so that it will start