Fuel Filter: Description and Operation

Fig. 31 Fuel filter:

Diesel fuel systems operate reliably as long as the fuel is free from dirt and water. Internal components inside the injection pump and injectors can be damaged by a small amount of dirt or corrosion.
The diesel fuel filter is designed to allow unrestricted flow of fuel from the tank but stops any dirt or water before it reaches the pump.
The replaceable element is similar to an oil filter. It threads onto a removable flange in the engine compartment, Fig. 31.
Some filter elements have a water drain in the bottom. If poor quality fuel is used, water separated by the filter can be drained to prevent freezing and blocking of the filter in cold weather.