A positive displacement gear-type fuel pump is
attached to the governor or blower on the In-line
engines and to the flywheel housing on the V-type
A spring-loaded relief valve, incorporated in the pump
body, normally remains in the closed position,
operating only when the pressure on the outlet side (to
the fuel filter) becomes excessive due to a plugged
filter or fuel line.
The fuel pump incorporates two oil seals. Two tapped
holes are provided in the underside of the pump body,
between the oil seals, to permit a drain tube to be
attached. If fuel leakage exceeds one drop per minute,
the seals must be replaced. An authorized Detroit
Diesel Allison Service Outlet is properly equipped to
replace the seals.
Fuel pumps are furnished in either left or right-hand
rotation, according to the engine model, and are
stamped RH or LH. These pumps are not interchange-
able and cannot be rebuilt to operate in an opposite
Fuel Strainer and Fuel Filter
A replaceable-element type fuel strainer and fuel filter
Fig. 4 - Typical Fuel Strainer and Filter
(Fig. 4) are used in the fuel system to remove
impurities from the fuel. The strainer removes the
larger particles and the filter removes the small
soaked in clean fuel oil, over the stud and push it
down on the seat. Close the drain cock and fill the shell
approximately two-thirds full with clean fuel oil.
The fuel strainer and fuel filter are basically identical
in construction, both consisting of a cover, shell and
5. Affix a new shell gasket, place the shell and element
replaceable element. Since the fuel strainer is placed
into position under the cover and start the cover nut
between the fuel supply tank and the fuel pump, it
on the shell stud.
functions under suction; the fuel filter, which is
installed between the fuel pump and the fuel inlet
6. Tighten the cover nut only enough to prevent fuel
manifold in the cylinder head, operates under
7. Remove the plug in the strainer or filter cover and
Replace the elements as follows:
fill the shell with fuel. Fuel system primer J 5956 may
be used to prime the fuel system.
1. With the engine shut down, place a suitable
container under the fuel strainer or filter and open the
8. Start and operate the engine and check the fuel
drain cock. The fuel will drain more freely if the cover
system for leaks.
nut is loosened slightly.
2. Support the shell, unscrew the cover nut and remove
Spin-On Type Fuel Filter
the shell and element.
A spin-on fuel strainer and fuel filter (Fig. 5) is used
3. Remove and discard the element and gasket. Clean
on certain engines. The spin-on filter cartridge consists
the shell with fuel oil and dry it with a cloth or
of a shell, element and gasket combined into a
unitized replacement assembly. No separate springs or
4. Place a new element, which has been thoroughly
seats are required to support the filters.