TM 5-3805-280-24-2
Fuel System Operation and Tests
115
A--Fuel Supply (Transfer)
C--Final Fuel Filter
F--Supply Pump Pressure
H--Fuel Return Leak-off
25
Pump
D--Fuel Injection Nozzles
Fuel
I--Suction Fuel from Tank
B-- Primary Fuel
E--Fuel Injection Pump
G--Injection Pressure Fuel
Filter/Water Separator
Incorporated into the fuel system is a means of
Refer to illustration on previous page.
returning excess (or unused) fuel (H) back to the fuel
tank. Excess fuel comes from two sources:
The fuel supply pump (A) draws fuel from the tank and
pressurizes it. This pressure permits the fuel to flow
1. Fuel Injection Pump: A quantity of fuel greater than
through the optional primary filter (B) and final filter (C)
that required by the engine is supplied to the fuel
and charge the transfer pump of the injection pump
injection pump.
(E).
2. Fuel Injection Nozzles: A small amount of fuel
seeps past the nozzle valve for lubrication
With the fuel injection pump charged with fuel by the
purposes.
fuel supply pump, the injection pump plungers
pressurize the fuel to approximately 50 000 kPa (500
To get the excess fuel back to the tank, a return line
bar) (7255 psi). Delivery (pressure) lines are used to
from the injection pump is connected to the middle of
route this high pressure fuel to the fuel injection
the nozzle leak-off line. Fuel from both sources is then
nozzles (D).
returned to the tank by a return pipe connected to the
front end of the leak-off pipe.
Fuel enters the injection nozzle at a pressure which
easily overcomes the pressure required to open the
nozzle valve. When the nozzle valve opens, fuel is
forced out through the orifices in the nozzle tip and
atomizes as it enters the combustion chamber.
RG,115,JW7716 1924NOV972/2
13-552
