The function of the gasoline filter is to filter out the moisture and impurities in the gasoline. When the engine is working, the fuel passes through the fuel inlet pipe and enters the sedimentation cup of the filter under the action of the gasoline pump. As the volume becomes larger and the flow rate becomes smaller at this time, the water and impurity particles heavier than the oil settle at the bottom of the cup. The light impurity flows to the filter element with the fuel, and the clean fuel penetrates into the inside of the filter element from the pores of the filter element. Flow out through the tubing. There are two types of filter elements: porous ceramic and paper. The paper filter element is made of microporous filter paper treated with resin, which has high filtration efficiency, low cost and easy replacement, so it is widely used.

Gasoline filters are divided into carburetor type and electronic injection type. For gasoline engines using carburetor, the gasoline filter is located on the inlet side of the fuel transfer pump and has a low working pressure. Generally, nylon shells are used. The gasoline filter is located on the outlet side of the fuel transfer pump and has a higher working pressure, usually with a metal casing. The filter element of gasoline filter mostly uses filter paper, but also uses nylon cloth and polymer materials.