The diesel filtration system is essential to the proper functioning and operation of a diesel fuel system. Without the fuel filters, the fuel can become loaded with particulates that can damage or corrode the engine and/or other various components of the diesel fuel system.

What are they?

Diesel fuel filters are often referred to as full-flow filters because they handle the entire amount of fuel, i.e. all of the fuel must pass through the filters before it reaches the diesel fuel pump. The diesel filtration system is often a multi-stage process, in which the fuel is separated from any particulates that may have been introduced while filling the tank or passing through the fuel lines. Fuel filters are necessary for any fuel system, not just diesel. However, fuel filters are extremely important in diesel systems because of the higher viscosity of diesel fuel compared to gasoline. Diesel fuel also contains more gum and particulates that can cause damage to the injection pump. Some diesel fuel filters are also equipped with a valve that releases the air that collects in the filter.

The filtration process

Most diesel engines are designed with a multi-stage filtration process, usually two stages, but sometimes three. The first filter, known as the primary filter is usually located between the fuel tank and fuel supply pump in most diesel engines. The primary filter uses a coarse material that removes any of the larger particles from the fuel while the smaller particulates are allowed to pass through. The particulates and any accumulated water will fall to the bottom and can be released through a drain plug. Most diesel engines are equipped with a pressure gauge that will indicate when the filter is dirty and needs to be cleaned.

The second filter stage, known as the secondary filter, is typically located between the fuel supply pump and injection pump. The secondary filter uses a finer material that rids the fuel of any smaller particles that passed through the primary filter.



Fuel filters are able to withstand a minimum internal differential pressure of 75 pounds per square inch and are necessary to keep your engine running smoothly.

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