The basic requirement for problem-free motoring is clean fuel. The fuel arrives in the injection system or in the carburettor via the fuel pump. Particularly in modern injection systems, dirt particles in the fuel cause increased wear. The water contents in the fuel can also cause serious damage as a result of corrosion. At worst, this can result in the complete failure of the injection system, bringing the vehicle to a standstill. Wear on the injection system or on the carburettor results in a considerable increase in fuel consumption and in impaired engine performance. The importance of the filtration with high pressures increases gradually in the injection elements that obtain a work without any problem by holding the particles outside of the system. Fuel filters supply the safe work and protection of the injection system and carburetor. There are two types of fuel filters: 1) Element Type Fuel Filter – they are assembled to engine in a protector and changed while maintenance. They are used for diesel engines. 2) Spin-On Type Fuel Filters – they consist of a filter element and a case. According to the filtration capability felt, filter paper and creep paper are used as filtration material. By playing the most important role in the clearance of the fuel, the fuel filters decrease the given harm to environment.