3-63. FUEL PUMP TESTING AND CALIBRATION (Contd)
m. AFC Plunger Setting Procedures (Contd)
Flowmeter glass tube (38)
Allow fuel to escape until float in
tube stabilizes at or near zero.
Air pressure during AFC plunger setting procedures must always be reached while
increasing air pressure on the AFC bellows. If specified pressure reading is overshot,
reduce the pressure to 0 in. Hg. (0 kPa) on fuel pressure gauge (2), and wait until the fuel
flow stabilizes at or near zero in flowmeter glass tube before increasing or decreasing the
Pressure regulator (9)
Adjust to increase air pressure
reading on pressure gauge (8) to
exactly 10.00 in. Hg. (36,000 kPa).
100. Flow control valve (37)
Adjust until fuel flow through
flowmeter glass tube (38) is
exactly 385 pph as indicated by
float in tube.
The AFC adjusting tool must be used with care. The large movable center hex socket
engages the nut that retains the AFC bellows to the plunger. Use a hex-head socket
wrench to move the plunger in and out to attain the proper adjustment.
If large hex socket is not properly engaged, the AFC bellows can be torn or ripped. The
proper sequence is to first engage the large hex socket, then the smaller hex socket, and
finally the hex-head socket wrench.
If adjustment is required, reduce air pressure to 9 psi (62 kPa).
101. AFC adjusting tool (91)
a. Using adjusting tool, adjust
AFC adjusting tool (91) is part of
fuel pressure reading on fuel
AFC fuel pump adjusting tool kit
pressure gauge (2) to a reading of
(3375189). During this adjustment,
83-87 psi (572-599 kPa).
it may be necessary to adjust the
flow control valve (37) to maintain
the fuel flow rate of 385 pph. Use
extreme care; fuel flow rate must
be maintained during tightening to
an approximate value of
25-35 lb-in. (2.8-3.9 Nm).
The AFC plunger can be very easily broken when tightening the jamnut. Use extreme care
when tightening three jamnuts to the required 25-35 lb-in. (2.8-3.9 Nm) torque. The large
and small hex sockets must be fully retracted after loosening the plunger jamnut to avoid
interfering with the AFC piston travel. If the AFC piston position is disturbed while
adjusting the plunger, repeat the entire adjustment sequence (steps 94 through 101).