S h o p Notes 2.0
DETROIT DIESEL 53
LOCATING AIR LEAKS IN FUEL LlNES
Air drawn into the fuel system may result in uneven
improper fuel line connections such as a fuel pump
suction line connected to the short fuel return tube in
running of the engine, stalling when idling, or a loss
the fuel tank which would cause the pump to draw air.
of power. Poor engine operation is particularly
noticeable at the lower engine speeds. An opening in
Presence of an air leak may be detected by
the fuel suction lines may be too small for fuel to pass
observation of the fuel filter contents after the filter is
through but may allow appreciable quantities of air to
bled and the engine is operated for 15 to 20 minutes at
a fairly high speed. No leak is indicated if the filter
shell is full when loosened from its cover. If the filter
Check for loose or faulty connections. Also check for
shell is only partly full, an air leak is indicated.
When installing fuel lines, it is recommended that
Flexible fuel lines are used in certain applications to
connections be tightened only sufficiently to prevent
facilitate connection of lines leading to and from the
leakage of fuel; thus flared ends of the fuel lines will
fuel tank, and to minimize the effects of any vibration
not become twisted or fractured because of excessive
in the installation.
tightening. After all fuel lines are installed. the engine
should be run long enough to determine whether or
Be sure a restricted fitting of the proper size is used to
not all connections are sufficiently tight. If any leaks
connect the fuel return line to the fuel return
occur, connections should be tightened only enough to
manifold. Do not use restricted fittings anywhere else
stop the leak. Also check filter cover bolts for tightness.
in the fuel system.
SEC. 2.0 Page 5