4-11. Engine Fuel System
4-13. Fuel Injector
a. General. When improper fuel injection is
Fuel for the engine fuel system comes from the fuel
supply tank, through the supply line, to the fuel strainer,
suspected of affecting the engine operation a systematic
to the fuel pump. The fuel leaves the fuel pump under
check should be made to determine the cause. The most
pressure and is forced through the fuel filter into the fuel
likely cause is dirt or water in the fuel. Drain sediment
manifold and through fuel pipes to the fuel injectors.
from the diesel fuel tank and drain the fuel filter housing.
Surplus fuel returns through outlet fuel pipes into the
return manifold and back to the fuel tank.
the engine still malfunctions check the fuel injectors as
4-12. Rocker Arm Cover
b. Priming the Fuel System.
(1) If fuel flow is broken and air enters the fuel
rocker arm cover.
system, the fuel system must be primed. Air in the fuel
b. Inspection. Inspect the rocker arm cover for dents
system will cause hard starting and misfiring.
or cracks. Replace defective rocker arm cover.
(2) Prime the fuel system by removing the plug in the
top of the filter and slowly filling the filter with fuel.
(1) Clean gasket area and install a new gasket.
c. Fuel Injector Checks
(2) Refer to figure 4-2 and install the rocker arm
(1) Before removing injector valve an elimination
procedure should be followed to determine which injector
(2) Push unit injector plunger all the way down with a
screwdriver to cut out the cylinder, if one is found where
holding the injector all the way down makes no difference
in irregular engine operation or cause exhaust smoke to
cease, probably, only that particular injector is defective.
(2) Refer to figure 4-3 and remove the fuel injector
(a) Remove the fuel pipes from both the injector
and the fuel connectors.
(b) Install clean shipping caps on the injector fuel
inlet and outlet and on the fuel connectors.
(c ) Remove rocker shaft bracket bolts and
swing rocker arms away from the injector.
(d) Remove injector clamp bolt, washer and
(e) Loosen adjusting screws on injector control
rack lever and slide lever away from the injector.
(f) Lift injector from its seat in cylinder head.
(g) Cover injector hole in cylinder head to keep
foreign material out.
(h) Clean the exterior of the injector with fuel oil
and dry with compressed air.
Figure 4-2. Rocker arm cover, removal and installation.