stop contaminants (rust, water, corrosion, and dirt) from entering the carburetor,
throttle body, injectors, injections pumps, and any other parts that may be damaged by
foreign matter. Fuel filters can be located in the following locations (fig. 4-6):
fuel strainer is also located in the fuel tank on the end of the pickup tube.
the fuel line right after the electric fuel pump.
the fuel line fitting in the carburetor.
the fuel pump.
the fuel line before the carburetor or fuel injectors.
When in doubt
about the location of the fuel filter, refer to the service manual.
operate by passing the fuel through a porous filtering medium (fig. 4-7).
The openings in the porous material are very small, and, therefore, any particles in the
fuel that are large enough to cause problems are blocked. In addition to the filtering
medium, the filter, in some cases, also serves as a sediment bowl. The fuel, as it passes
through the filter, spends enough time in the sediment bowl to allow large particles and
water to settle out of it.
of fuel filters are used today. They are the replaceable in-line, the replaceable in-line
in the carburetor, and the glass bowl (fig. 4-8). The most
common configuration is the replaceable in-line filter. these are in-line filter elements
that fit in the carburetor inlet or inside the fuel tank. Fuel filter elements can be made
from treated paper, ceramics, sintered bronze, or metal screen (fig. 4-9).
However, there is one filter element that differs from the others. It consists of a
stacked pile of laminated disks that are spaced 0.0003 inches apart. As the fuel passes
between the disks, foreign matter is blocked out. These filters are replaced when the flow
of fuel is restricted.
service involves periodic replacement or cleaning of system filters. It may also include
locating clogged fuel filters that are upsetting fuel system operations. Paper elements
must be replaced when clogged or after prolonged use. Sintered bronze fuel filters can
usually be cleaned and reinstalled. A clogged fuel filter can restrict the flow of fuel to
the carburetor or injectors. Engine Performance problems will show up at higher speeds.
filters have a check valve that opens when the filter becomes clogged. This will allow
fuel contaminants to flow into the system. When contaminants are found in the filters and
system, the tank, the pump, and the lines should be flushed with clean fuel.
to the service manual for information concerning service intervals, cleaning, and
replacement of all system filters.
Figure 4-6.Typical fuel filter
4-7.Fuel filter operation.
4-8.Fuel filter configurations.
4-9.Fuel filter elements.