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 engines.
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
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
interchangeable and cannot be rebuilt to operate in an
Fuel Strainer and Fuel Filter
A replaceable-element type fuel strainer and fuel filter
Fig. 4 - Typical Fuel Strainer and Filter Mounting
(Fig. 4) are used in the fuel system to remove
impurities from the fuel. The strainer removes the
3. Remove and discard the element and gasket. Clean
larger particles and the filter removes the small foreign
the shell with fuel oil and dry it with a cloth or
The fuel strainer and fuel filter are basically identical in
4. Place a new element, which has been thoroughly
construction, both consisting of a cover, shell and
soaked in clean fuel oil, over the stud and push it down
replaceable element. Since the fuel strainer is placed
on the seat. Close the drain cock and fill the shell
between the fuel supply tank and the fuel pump, it
approximately two-thirds full with clean fuel oil.
functions under suction; the fuel filter, which is installed
between the fuel pump and the fuel inlet manifold in the
5. Affix a new shell gasket, place the shell and element
cylinder head, operates under pressure.
into position under the cover and start the cover nut on
the shell stud.
Replace the elements as follows:
6. Tighten the cover nut only enough to prevent fuel
With the engine shut down, place a suitable
container under the fuel strainer or filter and open the
drain cock. The fuel will drain more freely if the cover
7. Remove the plug in the strainer or filter cover and fill
nut is loosened slightly.
the shell with fuel. Fuel system primer J 5956 may be
used to prime the fuel system.
2. Support the shell, unscrew the cover nut and remove
the shell and element.
8. Start and operate the engine and check the fuel
system for leaks.