TM 5-4520-208-15
Section XIII. HEATER FUEL SYSTEM (BT400-40-1)
89. General
steps (1) through (4) above.
The heater fuel system consists of a fuel
(12) Disconnect pressure hose assembly (8)
tank mounted in the base, fuel filter, tube as-
from tee installed in step (6) above.
semblies, fuel pump, fuel control box, and
(13) Remove tee, flexible hose and pres-
combustor.
sure gage, installed in step (6) above.
(14) Connect pressure! hose assembly (8) to
90. Fuel Pump and Heater Fuel Tube
elbow on underside of fuel pump. Per-
Assemblies
form steps (7) and (8) above
a. General The fuel pump is mounted on a
bracket to the left of the nozzle, The pump is
power unit.
belt driven by the power unit. A flexible hose
c. Flow Test.
assembly delivers fuel, through the fuel filter,
to the fuel pump. During the heating cycle
fuel travels from the pump to the nozzle and
(2) Disconnect secondary bypass tube as-
secondary bypass line. Bypass fuel `is returned
to the fuel tank from the nozzle and secondary
Disconnect tube assembly entering fuel
bypass line.
tank adjacent to fuel cap. Connect a
b. Pressure Test and Adjustment.
flexible tube or hose to fuel tube as-
(2) Disconnect secondary bypass tube as-
(3) Obtain two liquid containers, each hav-
ing at least. a one gallon capacity. Mark
(5).
one container to show quantity of one
(3) Disconnect primary bypass assembly
gallon. Place hose or flexible tubes
(2) from coupling (3).
leading from tube assemblies in un-
(4) Loosen two screws (7) and move fuel
marked container.
pump (4) toward center of heater.
(4) Close the damper (fig 13) by loosen-
(5) Disconnect pressure hose assembly (8)
ing and moving handwheel all the way
from elbow on underside of fuel
to the left (when facing discharge
pump.
end).
(6) Connect a tee, flexible hose, and pres-
(5) Set the temperature selector indicator
sure gage with a maximum reading of
knob (fig. 11) for a discharge air tem-
200 psi between elbow and pressure
perature of 150F. Start the heater
hose assembly (8).
lector indicator knob as necessary until
two screws (7).
discharge air temperature is stable at
(8) Connect secondary bypass tube assem-
150F.
bly (6) to connector (5) and primary
(6) When the temperature is stable, trans-
bypass tube assembly to coupling (3).
fer the hose or flexible tube to the
measuring container. Record the time
necessary for a flow of one gallon.
start the heater, observing pressure
gage reading. The pump should be op-
(7) If the time required to measure one
erating at 150 psi, plus or minus 2
psi.
gallon of flow is more than five min-
utes, replace the fuel pump.
(10) If the reading is not within operating
pressure tolerance, remove nut (1)
and turn adjusting screw clockwise to
connect hose or flexible tube from
increase pressure, or counterclockwise
fuel lines and connect tube assemblies
to decrease pressure.
to fuel tank.
58