While it is commonly referred to as a fuel filter, the fuel filter is indeed present on all vehicles equipped with an internal combustion engine . Despite its rather small size, it plays an extremely important role in the operation of a vehicle’s engine since it filters the particles found in the fuel. These can come from different sources, but they cause the same effects on the carburetor or the injection system if they are not eliminated. This is probably why the quality of fuel filters has improved a lot in recent years. Like the oil filter, the condition of the fuel filter should be checked regularly in order to replace it when necessary.


  • All about the fuel filter
  • Composition of fuel filters
  • Where do impurities come from?
  • How to control the quality of filtration?
  • What are the risks when driving with a used fuel filter?

All about the fuel filter

The fuel filter’s job is to remove impurities, residues, or even rust, which are often present in the fuel. These various elements can also infiltrate into the tank when a driver quietly fills the tank of his vehicle or even into the fuel pump. Thanks to its action, the fuel filter helps preserve the carburettor or the injection system, which are very sensitive to the level of fuel purity, by acting as a particulate filter.

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Composition of fuel filters

Like the oil filter, a vehicle’s fuel filter consists of a cylindrical-shaped metal casing inside, which is a cartridge comprising a filter made of paper or felt, which can be either wrapped around a metal tube (axial filters) or positioned in the shape of a star around a central axis (radial filters). The fuel will enter the filter through its upper part and then flow through the paper filters, whose excellent weave will retain much more impurities than an oil filter before exiting again through the upper part of the housing.

Where do impurities come from?

How can such particles get into the tank and mix with a vehicle’s fuel? Several origins are possible, and they can come from:

  • the vehicle design phase,
  • the repair of one of the mechanical elements,
  • flow from the tank ventilation system,
  • the oxidation phenomenon of the reservoir or one of the conduits which feed it
  • water condensation in the tank.

How to control the quality of filtration?

If for years vehicles (and more particularly cars) were satisfied with a fundamental particle filtration system, this is no longer the case today. Automobiles operating using joint rail injection and piezoelectric controlled injectors require the use of ever more efficient fuel filters. Otherwise, it would lead to many cases of engine failures. When we know the high cost of this type of repair, we can easily understand why it is imperative, for vehicle manufacturers and owners alike, to ensure that the filtration quality is always there.

Fuel filter maintenance

To know precisely when to replace a vehicle’s fuel filter, all you have to do is consult the manufacturer’s recommendations which appear in the maintenance manual. However, mechanical professionals agree that it should be replaced every two years, or every 40,000 kilometres travelled, for vehicles equipped with a carburettor and approximately every two years for cars. Vehicles, which are equipped with an injection system. The best way to check the condition of this filter is to change the engine oil. Thus, if the filter is found to be clogged, scaled or contaminated with water, it will have to be replaced. Symptoms such as the “jerking” sensation coming from the engine, complicated starting and idling anomalies also indicate the need to replace the fuel filter.

Only drivers with mechanical skills know this, but the fuel filter in diesel vehicles needs to be replaced more often than the one in gasoline cars. Diesel fuel comprises several diverse and harmful materials, including water, which considerably increases the risk of corrosion. If we add the mechanical complexity of this type of engine, we can easily understand that all this leads to more rapid wear.

What are the risks when driving with a used fuel filter?

When road users continue to drive a vehicle whose fuel filter should have been changed for some time now, they expose their car to several risks, the seriousness of which can go so far as to cause injury—engine failure.

Among the various symptoms that a dead fuel filter can cause, it is possible to find: 

  • the emission of white smoke at the level of the exhaust
  • excessive fuel consumption
  • rapid degradation of the injection system, with the appearance of corrosion in particular
  • a carburetor obstruction
  • reduced acceleration due to the partial absence of fuel injection

To avoid all these problems, it is necessary for road users to regularly monitor the condition of their fuel filter and replace it when its condition no longer allows driving—optimum of their car.