How a Car’s Fuel System Works

If you want to be technical, it starts at the tank when you remove the gas cap and pump fuel in. From here it enters the fuel pump, where the real action begins. Depending on the vehicle in question, this pump can sometimes be located inside of the gas tank, or attached to it. Some cars even have multiple fuel pumps to help keep a steady supply of fuel for the engine if fuel happens to be pooled on one side of the tank, like what can happen when a car is parked on a steep incline.

The fuel pump does what’s expected of it and pumps fuel that will eventually reach the engine. This fuel first has to travel through metal fuel lines, which run from the tank to the engine, as these two components are typically on opposite sides of the vehicle.

Diesel and gasoline are very different fuels, but they both have impurities in them when you first pump fuel into your car. That’s where the fuel filter comes in. As fuel is pumped through, the filter’s media captures impurities that could damage the engine while allowing the fuel to pass right through.

After the filter has removed any contaminants, it is time for the fuel to go to the engine where it can finally be of use. There are a few different ways the fuel can go into the engine. Which way your car does it is likely a matter of when your car was built.

• Carburetors used to be the most common way of getting fuel into the engine. The carb had a float that would raise up to allow gas to enter the engine at different rates, depending on how open the float was.
• Fuel injectors handle supplying fuel to almost all modern engines. These devices can be either mechanical or electronic, but electronic fuel injection is the only common method today. Electronic fuel injectors are controlled by the ECU, and can inject fuel with far greater precision than a purely mechanical carburetor because the ECU has total control.

Once the fuel is in the engine, it can be combusted and expelled through the vehicle’s exhaust system.