Operation CHARM: Car repair manuals for everyone.

Fuel Filter: Description and Operation

EFI Fuel Filter:






In-line Fuel Filter:
The fuel filter, located in the engine compartment, is a relatively large filter in comparison to its carbureted counterpart. Clean fuel is essential to the operation of the fuel injection system, as even small particles of dirt can plug the orifices of the fuel injectors. The filter contains a fine paper element with a medium pore size of 10 micrometers, backed by a strainer that catches any loose particles and is supported by a steel plate.

The filter is replaced as a complete unit, not as an insert. The outer steel shell is designed to withstand high system fuel pressure and is attached to the fuel hoses by threaded "banjo" type fittings. The filter is labeled with direction-of-flow arrows to ensure proper installation.


In-tank Fuel Filter
A woven plastic filter is located on the lower end of the fuel pick-up pipe in the fuel tank. This filter prevents dirt from entering the fuel line and also stops water from entering the fuel system, unless the filter becomes completely submerged in water. This filter is self-cleaning and normally requires no maintenance. Fuel blockage at this point indicates that the fuel tank contains an abnormal amount of sediment or water. Therefore, the fuel tank should be removed and thoroughly cleaned and the tank filter replaced.