A fuel filter is a simple device that is installed in a fuel system to screen out contaminants. Usually, it is a metal or plastic can that contains a filtration element. Fuel from the gas tank enters the filter and comes out clean and ready to be used in the engine.

Fuel filters have existed throughout the history of internal combustion engines. The early filters were are small plastic can. This design was suitable for the engines of that time. With fuel passing through the filter under low pressure, there was no need for an elaborate or high-strength device.

Today, the fuel filter is a slightly different design. With the introduction of direct-injected engines, there was the need for a filter that could withstand the high pressure levels in the fuel system. The modern filter is, therefore, stronger in many ways.

The outside shell is made from better material, the filtration media more robust and protected, and the whole filter assembly shielded from situations of excessive pressure by special relief valves.

These features mostly apply to the fuel filter that is fitted outside the fuel tank on the engine bay or fuel line. Commonly known as inline fuel filters, they have to withstand the different conditions, both inside and outside. Filters that mount in the fuel tank mostly have to bear the different fuel blends. They are, therefore, designed to put up with the specific environment.