Do not bend the fuel pipes and do not exceed the specified torque. Excessive tightening will twist
or fracture the flared ends of the fuel pipes and result in leaks. Lubricating oil diluted by fuel oil
can cause serious damage to the engine bearings.
Time the injector, position the injector rack control lever and adjust the exhaust valve clearance (cold setting) as outlined in
the engine tune-up procedure. If all of the injectors have been replaced, perform a complete tune-up on the engine.
A positive displacement gear-type fuel pump is attached to the governor or blower on the In-line 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 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 interchangeable and cannot be rebuilt to operate in an opposite rotation.
Fuel Strainer and Fuel Filter
A replaceable-element type fuel strainer and fuel 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 foreign particles.
The fuel strainer and fuel filter are basically identical in construction, both consisting of a cover, shell and replaceable
element. Since the fuel strainer is placed between the fuel supply tank and the fuel pump, it functions under suction; the
fuel filter, which is installed between the fuel pump and the fuel inlet manifold in the cylinder head, operates under
Replace the elements as follows:
1. With the engine shutdown, place a suitable container under the fuel strainer or filter and open the drain cock. The
fuel will drain more freely if the cover nut is loosened slightly.
2. Support the shell, unscrew the cover nut and remove the shell and element.