Auto Service World
Feature   July 1, 2001   by Auto Service World

COVER STORY: Fuel Filter 101


Fuel filters are essential in helping to protect fuel system components from contaminants that may be in the fuel. These contaminants can plug fuel injectors or carburetors, causing engine malfunction and deterioration.

Dirt, rust, scale and water are the major impurities present in fuel. These impurities can originate from dirty and rusty service station storage tanks and, as the vehicle ages, from corrosion within the fuel system components. All of the fuel that enters the engine must first pass through the fuel filter.


Fine particles, free water and emulsified water must be removed from diesel fuel before it passes through the fuel injection system. Fuel from the fuel tank is routed through the filter where contaminants are removed.

If the filter is a fuel/water separator, the fine particles remain trapped in the filter media while the water droplets come together and fall to the bottom of the filter.