Home Products News Contact Us
Home > Supports > Diesel Engine > Basic Working Principle of Diesel Engine Fuel Filter

Basic Working Principle of Diesel Engine Fuel Filter

Oct. 18, 2019

The fuel filter of diesel engine can filter out the harmful impurities and moisture in the fuel system, protect the normal work of the engine, reduce wear and tear, avoid clogging and improve diesel engine life. Here, we are willing to share the basic working principle of diesel engine fuel filter.

Basic Working Principle of Diesel Fuel Filter

The purpose of any diesel fuel filter is to remove foreign particles as well as water. The use of a suitable filtration system on diesel engines is a must to avoid damage to closely fitted injection pump and injector components.  Filter's ability varies between the type and manufacturer. On diesel engines primary and secondary filters are used. The primary filter is capable of removing dirt particles down to 30 microns and the secondary filter between 10 to 12 microns. Secondary filters are available between 3 and 5 microns, which are used in severe service operations. The primary filter is usually located between the tank and the supply pump, the FWS is one type of the primary filters. The secondary filter between the supply pump and the injection pump.

Diesel fuel filter is referred to as full-flow filter, because all the fuel must pass through it before reaching the injection pump. Some filters use internal replaceable element inside a bowl or shell. These are commonly referred to as a shell and element design. Most fuel filters used today are of the spin-on type, which allow for faster change out since the complete filter is a throwaway.

Besides, if the filter is installed on the pressure side of the boost pump it must have sufficient strength to handle pump pressure without bursting or leaking. The filter must be located well away from sources of heat, preferably outside of the engine compartment.


The fuel filter of diesel engine is mainly composed of three parts: filter element, the shell and filter base (As shown in Figure 1). All models are universal except for the overflow valve 8 that has two structures. Choosing C0810A or C0810B filter should be on the basis of different models. For the 12 cylinder V type diesel genset, it should be installed in parallel with each one of C0810A and C0810B.

fuel filter assembly section

Figure 1: Fuel filter assembly section

1. Gasket  2. Base of filter  3. Pull rod  4. Bleed screw  5. Gasket  6. Pull-rod nut  7. Jump ring  8. Overflow valve   9. Oil pipe connection  10. Seal ring  11. Sealing washer  12. Filter element  13. Seal ring  14. Tray  15. Spring seat  16. Shell  17. Seal ring  18. Spring

The fuel is sent to the fuel filter mainly by the fuel pump. The impurities in the fuel will be cleared through the paper filter element. And then the fuel can enter the inner cavity of the filter cylinder. Through the collection chamber of the filter sea, it leads to the fuel injection pump. The filter holder is equipped with fuel return fitting and the overflow valve is also installed inside. When the fuel pressure in the fuel filter is more than 78kPa(0.8kgf/C㎡), the excess fuel will return back to the fuel tank from the fuel return fitting. When connecting the low pressure fuel line, you should connect it according to the arrow pointing direction on the socket to avoid connection error. The filter seat and the shell are connected by pull rod, and it is sealed by rubber ring. Due to there is a bleeder plug on the top of filter seat, users can release the screw to clear the air of the fuel filter in use.

Fuel Filter overhauling

Figure 2: Fuel filter overhauling

The fuel filter of the diesel engine is fixed on the engine body and bracket with two M8-6H screws. If users find that the fuel supply is not smooth, it is possible that the filter element is pluged. At the moment, you should dump the fuel oil. You can directly loosen the pull rod nut of diesel generator set, remove the shell, and take out the filter cartridge (As shown in Figure 2). After the filter element is dipped into gasoline or diesel oil, you can gently wash the dirt off with brush (As shown in Figure 3). If the filter cartridge is broken or hard to clean, it must be renewed. Then install it as shown in Figure 1 and inject the clean fuel.

fuel filter cleaning

Figure 3: Cleaning fuel filter element

The basic working principle of fuel filter for diesel engine mentioned above is share by Jiangsu Starlight Electricity Equipment Co.,Ltd. Hope it is useful for all users. Besides, our company can provide a variety of specifications common from 3KW to 2500KW, automated, four-protection, automatic cut over, low noise and mobile and so on high quality, and the low energy consumption generator set so as to satisfy the customer all electric power demand. We can also satisfy the user different voltage, different frequency request, as well as many units and networking power supply system. 

Contact Us
  • Add.: Room 601, Laboratory Building, No.2 Gaohua Road, Nanning, Guangxi, China.
  • Tel.: +86 771 5805 269
  • Fax: +86 771 5805 259
  • Cellphone: +86 134 8102 4441
                    +86 138 7819 8542
  • E-mail: sales@dieselgeneratortech.com
Follow Us

Copyright © Guangxi Dingbo Power Equipment Manufacturing Co., Ltd. All Rights Reserved | Sitemap

Update cookies preferences


Contact Us