TM 5-2420-230-24-2
B3.9 and B5.9 Series Engines
Fuel Drain Line Restriction (006-012)
Section 6 - Injectors and Fuel Lines - Group 06
Page 6-5
Test (006-003-012)
A replacement of fuel supply lines, fuel filters, fuel injection
pump, high-pressure fuel lines, and injectors will let air
enter the fuel system. Air in the system will make the engine
hard to start, run rough, misfire, produce low power, and
can cause excessive smoke and a fuel knock.
NOTE: If an excessive amount of air has entered into the
system, the system will need to be bled.
Loosen the return banjo fitting on the fuel lift pump. Run the
fuel lift pump until all the air has been bled. When all the
air has been bled, retighten the fitting.
NOTE: To run the fuel pump for 25 seconds, crank the
engine for a split second, and leave the key in the ON
position.
If air continues to bubble out of the system for several
minutes, then an air leak is present.
An often overlooked source from which air can enter the
fuel system is between the inlet of the fuel transfer pump
and the suction tube in the tank. Fuel tanks that have the
outlet fitting at the top will have a suction tube that extends
to the bottom of the tank. Cracks or pin holes in the weld
that join the tube to the fitting can let air enter the fuel
system.
Also, check to make sure all the fittings from the fuel supply
line on the tank to the inlet of the fuel transfer pump are
tight.
Use a sight glass at the fuel lift pump inlet to check for air
in the fuel supply lines.
Fuel Drain Line Restriction (006-012)
Measure (006-012-010)
10 mm
Remove the capscrews from the hold-down clamps, and
complete the following steps:
L-975
