Be sure to keep the line clear of
moving engine parts (fan, pulleys, etc...)
and DO NOT place the line on the
Fuel lines should be inspected for kinks, cracks, or
anything that would restrict fuel flow or allow air into
the lines. Be sure to check the lines all the way
back to the tank and remember that there is a
strainer inside the tank which can also become
To teat for air leaks in the supply lines, disconnect
the return line from the injection pump and connect
a line that is long enough to reach the ground.
Place the end of the line into a bucket containing
diesel fuel, making sure that the end of the line is
below the level of fuel in the bucket. Run the
engine and watch for air bubbles in the bucket.
Replace fuel line, refer to (para 3-25).
An important function of all hoses, lines and fittings is to
carry fuel without admitting air to the system. When the fuel
tank cap is in place and the fuel pump and injection pump
are drawing fuel through the lines a low vacuum of 0-1 PSI
is created. This occurs because the fuel which the engine
uses must be replaced by air. During this vacuum
condition, the slightest leak, which may not leak fuel out,
could draw air into the system and, depending on the
volume of air, cause a wide variety of engine malfunctions.
COLD WEATHER OPERATION
Diesel fuel is sensitive to temperature. All diesel fuel has a
certain amount of wax-like components which have high
energy value and help improve fuel economy. When
temperatures are less than 20°F (-7°C) these components
begin turning into flakes that can build up on the fuel tank
strainer or in the fuel filter.
In warm or humid weather, fungi and/or bacteria can cause
fuel system damage by plugging the fuel lines, filter, or
Old fuel smells like varnish.
Check the accelerator pedal for full movement
with no sticking or binding. It you have sticking
or binding, lubricate accelerator pedal bushing
and bearing with seasonal grade OE oil
(TM 9-2320-280-10). If you do not have full
pedal travel then disconnect the accelerator
linkage from the fuel injection pump and recheck
the travel. It you now have full travel then the
problem is in the fuel injection pump and cannot
be handled at this level of maintenance.
Operation of the injection pump and injectors
cannot be verified at this level of maintenance.