TM 5-3895-382-24
NOTE:
If there is no fuel flow through the valve body of
the air inlet heater, the fuel injection pump could
be damaged. The fuel supply line to the heater
must also be free of air in order to prevent
damage. An air inlet heater that is damaged will
allow the fuel to drain into the inlet manifold when
the engine is running. This condition could cause
exhaust smoke. Excessive fuel could also cause
an overspeed condition.
Fuel Injector Nozzles For Type 1 Engines and 9RM
NOTE:
For a complete description of Type 1 and Type 2
engines, refer to the Systems Operation, Testing
and Adjusting Module, "Engine Design" for more
information.
Illustration 10
Fuel injector nozzles (typical example)
Table 5
(1) Fuel inlet
(7)
Spindle for spring
(2) Cap nut
(8)
Retaining nut for fuel injection
(3) Fuel return
nozzle
(4) Pressure adjusting screw
(9)
Needle valve
(5) Spring
(10) Nozzle
(6) Body
(11) Orifices
(12) Seat washer
Fuel flows under high pressure from the fuel injection pump
through the hole in the fuel inlet (1). The fuel then goes around
the needle valve (9) which fills the inside of the nozzle (10) with
fuel. The pressurized fuel pushes the needle valve (9) and the
spring (5) for the pressure adjusting screw. When the force of
the fuel pressure is greater than the force of the spring (5), the
needle valve (9) will lift up. When the needle valve (9) opens,
fuel under high pressure will go through the orifices (11) into
the cylinder.
When the fuel is sent to the cylinder, the force of the fuel
pressure in the nozzle body will decrease. The force of the
spring (5) will then be more than the force of the fuel pressure
in the nozzle body. The needle valve (9) will move quickly to
the closed position. Needle valve (9) has a close fit with the
inside of the nozzle. The close fit makes a positive seal for the
valve.
When the fuel is sent to the cylinder, a small quantity of fuel
will leak past the valve guide. This fuel lubricates the moving
parts of the fuel injection nozzle. This fuel then goes through a
passage in the body (6) to the fuel return (3). This excess fuel
is returned to the fuel tank.
Fuel Injector Nozzles For Type 2 Engines and 7BJ
NOTE:
For a complete description of Type 1 and Type 2
engines, refer to the Systems Operation, Testing
and Adjusting Module, "Engine Design" for more
information.
6-12
