The fuel filter performs the only and very common function in the car - it cleans the fuel of all sorts of physical pollution - cleanings, dust, outside fractions, and grains, in short, everything that should not get inside the internal combustion engine. It does nothing to change the other properties of the fuel.
The filter element is present in absolutely every car, regardless of whether the engine runs on petrol, diesel or gas - any type of fuel undergoes a gradual cleaning before it will be injected into the combustion chamber in the form of a fuel-air mixture or clean fuel. At the same time, cleaning is carried out in at least two stages — with the help of a coarse mesh filter and then - the main filter. The second is exactly usually subject to periodic replacement, the terms of which each manufacturer of a specific model of the car regulates independently. Let us dwell upon petrol variants of cars.
During refueling, fuel from the filling hose is filled directly into the tank. At this time, all the dirt from the fuelling nozzle gets into the tankage, as well as the dust. From the fuel tank, the relatively dirty fuel in modern cars is taken by an in-tank pump equipped with a nylon net, which does not allow the large fraction to get to the fuel line. Then the fuel gets into the main filter, which detains dangerous small particles for the injection system and the engine. Such cleaning is quite enough to ensure safe and reliable operation of the injection system and the entire motor during its full service life. All the car owner needs to do is to change the consumable from time to time, or rather, the filter.
Whatever the manufacturer's recommendations for replacing external filters, the real service life is very difficult to define - it entirely depends not only on the quality and area of the filter element but also on what the amount of pollution gets into the tank of your vehicle specifically. In practice, a remote fuel filter serves not less than 62 thousand miles without obvious indications for replacement. The in-tank filter, which is part of the fuel pump, does not need to be replaced at all until fuel problems occur. And this approach is entirely appropriate!
The filter element is working exactly just as long as it can provide the necessary amount of fuel to the rail and allows keeping the proper pressure in the system under different operating modes of the engine. While the filter element retains the ability to duct the necessary amount of fuel through itself, there are no real indications for replacing it.
- the engine does not rotate to high speeds (loses power);
- the car jerks when driving (there are passes in the fuel supply);
- the engine runs heavily (misfires);
- fuel consumption increases;
- the ignition is off for no apparent reason.
Please note that all these features are often caused by different problems not related to the fuel filter, so they can not be considered absolute indications for replacing this "consumable" without additional diagnostics.