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
Fuel filter 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.
Some fuel 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
Always refer to the service manual for information
concerning service intervals, cleaning, and replacement
of all system filters.
The fuel pump delivers fuel from the tank to the
engine under pressure. There are two basic types of fuel
pumpsmechanical fuel pump and electrical fuel
Mechanical fuel pumps are commonly used with
carburetor type fuel systems. They are the oldest type of
fuel pump, but they are still found on many vehicles.
The mechanical fuel pump is mounted on the side of the
engine block, using a gasket between the pump and the
block to prevent oil leakage. Since the mechanical
Figure 4-8.Fuel filter configurations.