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SP-10. BLEEDING THE FUEL SYSTEM
CAUTION: Escaping diesel fuel under pressure
can penetrate skin causing serious personal injury.
Before disconnecting lines be sure to relieve all
pressure. Before applying pressure, be sure all con-
nections are tight and lines, pipes and hoses aren't
damaged. Fuel escaping from a very small hole
can be almost invisible. Use a piece of cardboard
or wood, rather than hands, to search for suspected
leaks. If injured by escaping fuel, see a doctor at
once. Serious infection or reaction can develop if
proper medical treatment is not
administered immediately.
1. Fuel system air bleeding may be needed when:
a. After fuel has been added to a newly installed
engine.
b. A new fuel filter is installed.
c. The engine has run out of fuel.
d. The fuel lines, injection pump, or any other fuel
system component has been removed and
installed.
2. After changing the fuel filter, air only needs to be bled
from the fuel filter. To do this:
a. Loosen the air vent plug
filter by about 1-1/2 turns. (Be sure to cover the
vent with a cloth to prevent fuel from splashing.)
b. Turn the priming pump cap on the fuel feed pump
counterclockwise to unlatch it. Move the priming
pump plunger
(#2 on Figure 8)
close the pump turn the cap clockwise while
depressing it.
c. Close the air vent plug when no more air bubbles
can be seen in the fuel flowing from the air vent
plug hole.
Servicing
on the fuel
(#1 on Figure 8)
up and down. To
OM944W3 1/23
24
Figure 8 Fuel Feed Pump
3. To bleed air at the fuel injection pump:
a. Turn the air vent plug
turns to loosen it. (Cover the vent with a cloth to
prevent fuel from splashing.)
b. Pump the feed pump cap up and down.
c. When there are no air bubbles to be seen in the
fuel flowing from the air vent plug hole, push
down the priming pump cap and turn it clockwise
to lock it in place.
NOTE:
Do not close the air vent plug before locking the
priming pump cap in place, because the internal
pressure in the pump will prevent the priming
pump cap from returning to the original
position.
4. If the engine does not start after this bleeding
process, loosen a fuel line at the injector while
cranking the engine with the starter motor until
pure fuel escapes. Then tighten the connections.
Do each line one-at-a-time. After the engine has
started, use a piece of cardboard to look for fuel
leaks.
about 1-1/2
(#3 on Figure 8)
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