The function of the automobile fuel water separator is to remove the moisture in the diesel, so as to reduce the failure of the fuel injection nozzle and prolong the service life of the engine. Models that use high-pressure common rail engines under the Euro 3 Standards have higher requirements for diesel quality. Because high-pressure fuel injectors need to accurately control fuel injection pressure, fuel injection time and fuel injection volume, they require more refined workmanship. If there is water or impurities in the diesel fuel that are not filtered clean, it will cause wear and tear on the plunger and even parts of the fuel injector, until the fuel injector is stuck. The automobile fuel water separator is an instrument that separates diesel and moisture. Its working principle is mainly based on the density difference between water and fuel, using the principle of gravity sedimentation to remove impurities and moisture. In addition, it has separation elements such as diffusion cones and filters to enhance the effect of fuel water separation.

Failures caused by problems with the fuel water separator:
1. Engine acceleration is unstable, acceleration is weak, and black smoke is emitted. The high-pressure fuel injection nozzle in the high-pressure common rail system needs to accurately control the fuel injection pressure, fuel injection time and fuel injection volume, and the fuel injection nozzle has a finer workmanship. If there is a problem with the fuel water separator, the water and impurities in the diesel fuel will wear and tear the plunger and even parts in the fuel injector until the fuel injector is stuck. Damaged fuel injectors can cause unstable or weak acceleration of the engine, or failures such as black smoke emission. In severe cases, it will directly damage the engine. Due to the fine workmanship of the fuel injector, its price is relatively high. Based on the above reasons, when there is a problem with the fuel water separator, it must be replaced in time.
2. Coking If the fuel water separator is damaged, the water and impurities in the diesel will pass through the filter device, and then silt in the intake valve, intake duct, and cylinder, forming hard coke for a long time, which will affect the work of the engine, and in severe cases, it will cause the engine to be destroyed.
3. White smoke from the engine The damage of the fuel water separator will cause the engine to emit white smoke, because the water in the fuel will turn into water vapor when it is burned, so white smoke will appear. The water vapor in the white smoke will damage the high-pressure fuel injectors, resulting in insufficient engine power, and sudden shutdowns. In severe cases, the engine will be directly damaged.