The fuel system includes the fuel injectors, fuel pipes (inlet and outlet), fuel manifolds
(integral with the cylinder head), fuel pump, fuel strainer, fuel filter, and fuel lines.
Figure 4. Fuel System.
Fuel is drawn from the supply tank through the fuel strainer and enters the fuel pump at the inlet side. Leaving the
pump under pressure, the fuel is forced through the fuel filter and into the inlet fuel manifold, then through fuel
pipes into the inlet side of each fuel injector.
The fuel manifolds are identified by the words IN (top passage) and OUT (bottom passage), which are cast or
stamped in several places on the side of the cylinder head. This aids installation of the fuel lines. Surplus fuel
returns from the outlet side of the injectors to the fuel return manifold and then back to the supply tank.
All engines are equipped with a restrictive fitting in the fuel outlet manifold in one of the cylinder heads on the
engines to maintain the fuel system pressure. A check valve may be installed in the supply line between the fuel
tank and the fuel strainer to prevent fuel from draining back when the engine is shut down.
The fuel injector is a lightweight compact unit which enables quick, easy starting directly on diesel fuel and
permits the use of a simple open type combustion chamber. The simplicity of design and operation provides for
simplified controls and easy adjustment. No high pressure fuel lines or complicated air-fuel mixing or vaporizing
devices are required. The fuel injector performs four functions (times, atomizes, meters, and pressurizes):
Accurately times the moment of fuel injection.
Atomizes the fuel for vaporization and mixing with the air in the combustion chamber.
Meters and injects the correct amount of fuel required to maintain engine speed and to handle the load.
Creates the high pressure required for proper fuel injection.