allow bearings to seat-, and to purge all air
from the system.
(11) Before starting calibration, check pump
fuel flow-in the flowmeter for air. If air is
present, correct leak before continuing test.
(12) The test fuel oil must be 90 to 100F (32 to
(13) Set gear pump at 8 inches (203 mm) Hg.
vacuum during run-in.
(14) Calibration Procedure.
(a) Close idle, leakage, and pressure
valves. Open flow control or needle
valve wide open.
(b) Increase pump speed to engine rated
(c) Adjust vacuum valve in fuel pump
suction line to obtain 8 inches (203 mm)
Hg on vacuum gauge.
(d) If you cannot obtain 8 inches (203 mm)
of vacuum, check for restriction in test
stand filter or fuel supply line.
(e) Close the fuel manifold orifice valve
until the flowmeter shows 168 psi (1159
kPa) at 1800 rpm. There must be no air
visible in the flow- meter. Disregard
change in vacuum readings at this
(f) If flow cannot be obtained and held,
check idle plunger and governor break.
Inspect pulsation damper diaphragm.
(g) Open fuel pressure gauge valve. With
throttle in full fuel position, increase
pump speed until point at which fuel
pressure just begins to decrease (peak
point). This should occur at 2090 rpm.
(h) If speed is lower than specified, add
shims between governor spring and
retainer. To reduce speed, remove
Figure 13-25. Fuel Pump Damper, Exploded View