FUEL PUMP TESTING AND CALIBRATION (Contd)
c. Mounting Fuel Pump to Test Stand (Contd)
Governor spring pack
b. Install fuel pump idle
Use fuel pump idle adjusting tool
housing (43) (Contd)
adjusting tool (90) on governor
(3375981). To assure that gover-
spring pack housing (43).
nor has enough clearance to cut off
during calibration adjustments,
carefully pull tool shaft out so that
snapring is lightly resting against
stop. If too much force is put on
tool, snapring may be pushed off
tool shaft and down into fuel
pump main housing (51).
AFC cover plate (42) and
Remove from fuel pump main
AFC adjusting tool is part of AFC
housing (51) and replace with
fuel pump adjusting tool kit
AFC adjusting tool (91).
(3375189). Pull out knobs on tool
to disengage sockets. Relief cuts
on tool must face toward rear of
pump to allow clearance for AFC
fuel passage pipe plug (92).
Regulated shop air source
Connect to test stand (1).
Maximum pressure should not
exceed 40 psi (275 kPa).
Aneroid AFC adjusting line
Connect to AFC adjusting tool (91).
Some Big Cam I engines may have fuel pumps having the Air Signal Attenuator (ASA). For
those pumps, perform step 35. Big Cam III engine fuel pumps do not require step 35 to be
Air Signal Attenuator (ASA)
a. Calibrate the fuel pump
Smoke control valve produces a
and restrictor. (The ASA and
without the smoke control valve.
delay in intake manifold
restrictor are collectively
Valve is threaded into AFC cover
pressure signal to the AFC,
called the smoke control
plate (42). See illustration on next
resulting in a reduction of
When removing the ASA from the AFC cover plate, do not disassemble by placing the
wrench on top of the ASA. Place the wrench on the hex at the bottom of the ASA, just
above the top of the restrictor for disassembly.
b. Check valve by blowing
There should be free air flow when
through each side of valve.
blowing through the 1/8-NPT end of
valve (AFC cover plate end) and
restricted flow when blowing
through intake manifold end
(almost no air flow).
c. Check restrictor check ball for
Check ball is located in the
sticking by shaking it and
restrictor (41) to prevent a reverse
listening for check ball to rattle
fuel flow to the intake manifold if
in restrictor (41). If check ball is
AFC bellows ruptures.
stuck and not moving when
restrictor is shaken, replace the unit.
d. Check restrictor orifice by
If no air bubbles are coming out
connecting it to an air line.
of orifice, restrictor (41) is plugged
Immerse restrictor (41) in clean
or contaminated and should be
test fluid and pressurize it with