The fuel system in today’s vehicles can be complicated. To properly maintain the fuel system, it is important to understand its full function.

The fuel system stores and supplies fuel to the engine cylinders. The fuel is mixed with air and becomes vaporized, then it moves to the engine cylinders to be burned to produce energy. While a vehicle is running, there is a constant circulation of fuel from the fuel tank through the system and back.

Fuel is stored in the fuel tank where the fuel pump draws it and sends it through the fuel lines through a fuel filter to the fuel injectors (carburetors and throttle body injection were used on older vehicles). It is then delivered to the intake manifold to mix with air where it becomes a fine mist that is introduced into the cylinder for combustion. In direct injection vehicles, the fuel is directly injected into the cylinder. The exhaust gas recirculation system in a vehicle is designed to reduce the cylinder chamber temperature and to reduce nitrogen oxide emissions, which are more commonly known as NOX.

Before 1970, all vehicles had fuel tanks that vented to the atmosphere, emitting hydrocarbon emissions. After 1970, a charcoal canister was added that all fuel tanks would vent through. Then it is directed through lines into the engine to be burned before being released to the atmosphere. This is what we now call the Evaporative Emissions System.

In our next article, we will talk a little bit more about this Evaporative Emission System and the best way to maintain your vehicle’s fuel system.

Happy Motoring!

All About Automotive
139 NW 2nd Street
Gresham, OR 97030

Steve and Karen Johnston are owners of All About Automotive, providing auto repair and auto maintenance in Historic Downtown Gresham. If you have questions or comments, call them at 503-465-2926 or email them at [email protected].

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