adjustments, open main control valve to
flowmeter wide open and move throttle
lever back and forth until flowmeter
shows no air, so air may be expelled
more rapidly from system.
(15) Setting Idle Speed.
(a) Close test stand main flow control valve
and open idle orifice valve.
(b) Set throttle shaft in idle position (toward
gear pump) and hold firmly against stop.
(c) Run test stand at 168 psi (1159 kPa).
pressure gauge; it should be 168 psi
(1159 kPa). If pressure is low, screw
idle adjusting screw (16, figure 13-23) in
with the spring adjusting tool. To lower
pressure, back out screw.
(16) Weight Assist Pressure Check.
(a) Decrease pump speed to 800 rpm.
Adjust flowmeter if not as specified.
(b) The fuel manifold pressure should be
129 to 135 psi (890 to 931 kPa) at'1500
(c) If fuel pressure is low, add shims behind
the governor weight assist plunger in
the governor weight carrier (16, figure
13-12) or (24, figure 13-21). To
decrease pressure, remove shims. If
adjustments are required, recheck entire
pump calibration. Shims are available
in 0.007 to 0.016 inch (0.178 to 0.406
Weight assist plunger must be installed
with the smallest end to the governor
(17) Check Pressurizing Valve. Loosen the
plug (1, figure 13-23) in the governor
spring pack housing cover. Fuel should
leak around the plug if the pressure valve
is properly pressurizing the housing.
(18) Checking Pump Seals.
(a) With the test stand operating at 500
rpm, close vacuum valve in fuel pump
suction line until vacuum gauge reads
15 inches vacuum. The fuel flow
control valve should be open during this
(b) Put a small amount of light cup grease
over the vent hole at the mainshaft seal
bore of the mainshaft cover (30, figure
(c) If lubricant is sucked into the hole at the
15 inch vacuum setting, this is an
indication that the seals will not permit
proper engine performance and should
(d) During the above check, observe the
flowmeter for air in the meter which may
or may not indicate air leakage into the
pump. Air may be entering lines
between tank and pump. A slow leak
may not show up promptly as air in the
meter. Observe fuel level in tank for
possibility of low fuel causing air
(e) Leakage may occur at the gear pump to
housing gasket if gear pump is not
Tighten all capscrews,