The AMSOIL FFK60 Fuel Filter incorporates both
a primary and secondary filter for maximum fuel cleanliness. The
primary 10 micron filter, located in the Horizontal Fuel
Conditioning Module (HFCM), performs initial fuel cleansing before
sending the clean pressurized fuel to secondary four micron filter,
mounted to the oil filter housing.
The secondary fuel filter includes a fuel
pressure regulator and an orifice on top of the housing that bleeds
air out of the housing and back to the fuel tank. Following its trip
through the secondary filter, fuel is returned to the HFCM, where it
is either directed to the tank or returned to the primary filter.