and install the primer. Prime the system. Remove the
primer and install the filler plug.
Fuel Flow Test
The proper flow of fuel is required for satisfactory engine
operation. Check the condition of the fuel pump, fuel
The crankcase pressure indicates the amount of air
passing between the oil control rings and the cylinder
liners into the crankcase, most of which is clean air from
the air box. A slight pressure in the crankcase is
desirable to prevent the entrance of dust. A loss of
engine lubricating oil through the breather tube,
Fig. 3 - Inspecting Piston Rings
crankcase ventilator or dipstick hole in the cylinder block
is indicative of excessive crankcase pressure.
Engine Out of Fuel
The causes of high crankcase pressure may be traced
The problem in restarting an engine after it has run out
to excessive blow-by due to worn piston rings, a hole or
of fuel stems from the fact that after the fuel is
crack in a piston crown, loose piston pin retainers, worn
exhausted from the fuel tank, fuel is then pumped from
blower oil seals, defective blower, cylinder head or end
the primary fuel strainer and sometimes partially
plate gaskets, or excessive exhaust back pressure.
removed from the secondary fuel filter before the fuel
Also, the breather tube or crankcase ventilator should be
supply becomes insufficient to sustain engine firing.
checked for obstructions.
Consequently, these components must be refilled with
fuel and the fuel pipes rid of air in order for the system
Check the crankcase pressure with a manometer
to provide adequate fuel for the injectors.
connected to the oil level dipstick opening in the cylinder
block. Check the readings obtained at various engine
When an engine has run out of fuel, there is a definite
speeds with the Engine Operating Conditions on Page
procedure to follow for restarting it:
1. Fill the fuel tank with the recommended grade of fuel
NOTE: The dipstick adaptor must not
oil. If only partial filling of the tank is possible, add a
minimum of ten gallons (38 litres) of fuel.
be below the level of the oil when
checking the crankcase pressure.
2. Remove the fuel strainer cartridge and fill the
cartridge with fuel oil. Install the cartridge.
Exhaust Back Pressure
3. Remove and fill the fuel filter cartridge with fuel oil as
A slight pressure in the exhaust system is normal.
in Step 2.
However, excessive exhaust back pressure seriously
affects engine operation. It may cause an increase in
4. Start the engine. Check the filter and strainer for
the air box pressure with a resultant loss of efficiency of
the blower. This means less air for scavenging which
results in poor combustion and higher temperatures.
NOTE: In some instances, it may be
necessary to remove the valve rocker
Causes of high exhaust back pressure are usually a
cover and loosen a fuel pipe nut to
result of an inadequate or improper type of muffler, an
bleed trapped air from the fuel system.
exhaust pipe which is too long or too small in diameter,
Be sure the fuel pipe is retightened
an excessive number of sharp bends in the exhaust
securely before replacing the rocker
system, or obstructions such as excessive carbon
formation or foreign matter in the exhaust system.
Primer J 5956 may be used to prime the entire fuel
Check the exhaust back pressure, measured in inches
system. Remove the filler plug in the fuel filter cover
of mercury, with a manometer. Connect the manometer
to the exhaust manifold by removing the 1/8" pipe