Fuel filter is a crucial component of a car's fuel system, located between the fuel pump and the engine. Its primary function is to filter water and impurities (such as dust and rust) from the fuel, preventing them from entering and clogging fuel injectors, damaging the fuel pump and other precision components. This ensures normal and stable engine operation, reduces wear, and improves fuel efficiency. Fuel filters are categorized into gasoline filters and diesel filters, and come in external and internal types. Filter elements are made of various materials, and regular replacement (refer to the maintenance manual) is crucial; otherwise, starting and power will be affected.

Main Functions and Roles:
Filtering Impurities: Removes solid particles such as iron oxide, dust, and sludge from the fuel.
Protecting the System: Prevents clogging of fuel injectors and damage to the fuel pump and other precision fuel system components.
Preventing Water Damage: Filters water from the fuel,
preventing corrosion and engine damage.
Ensuring Engine Performance: Ensures a clean fuel supply, guarantees smooth engine power output, and reduces fuel consumption.

Types:
Gasoline Filter: Primarily filters impurities from gasoline.
Diesel fuel filter: Usually includes an oil-water separator, requiring higher standards for filtering water and impurities from diesel fuel.
External type: Installed in the chassis, mostly straight-through or with a return line.
Internal type: Located inside the fuel tank.
Spin-on type: The housing and filter element are integrated.
In-line/Replaceable filter type: Directly installed in the fuel line, or the filter element can be replaced separately.
Symptoms: Weak acceleration, insufficient power.
Difficulty starting, requiring multiple ignition attempts.
Engine vibration or unstable idling.
Long-term blockage may cause premature damage to the fuel pump.
Replacement cycle: Varies by vehicle model; refer to the vehicle's maintenance manual.
In areas with poor-quality fuel, the replacement cycle may be shortened. Generally, it is recommended to replace the fuel filter every 10,000-20,000 kilometers.