TM 5-2420-230-24-2
Fuel Manifold (Drain) (006-021)
B3.9 and B5.9 Series Engines
Page 6-10
Section 6 - Injectors and Fuel Lines - Group 06
Start the engine, and run at low or high idle.
Allowable Inlet Restriction at Low/High Idle
mm Hg
in Hg
101.6
MAX
4.0
If the fuel inlet restriction is too high, check to make sure
that the OEM lines from the tank are sized properly, there
are no kinks or bends in the lines, and the lines are not
clogged.
Make sure that there are no clogged fuel strainers or mal-
functioning check valves.
Fuel Manifold (Drain) (006-021)
General Information
The fuel system is designed to use fuel to cool and lubricate
the injection pump and injectors. Fuel is continually vented
from the injection pump, and a small amount of fuel leaks
near the injector needle valve during injection. This fuel is
returned to the supply tank by the fuel drain manifold.
Restriction of the fuel drain manifold can affect the Lucas
CAV DPA/DPS fuel injection pump metering controls and
the operation of the injectors. Restricting the fuel drain
manifold raises the case pressure of the fuel injection pump,
which can prevent injection.
If the engine will restart after a waiting period following an
unexplained shutdown, look for any restriction of the mani-
fold drain line.
NOTE: Restriction can cause the fuel temperature to rise,
reducing power from the engine.
L-980
