Paper operating temperature for calibration fluid is 90 F 100 F (32 C 57 C). The
test stand built-in thermometer automatically maintains that temperature once the
fluid has circulated.
(8) Turn fuel heat switch to ON position. Check that fuel heat light comes on. Monitor fuel temperature on fuel
temperature gage throughout testing and calibration of fuel pump.
(9) Adjust shop air pressure regulator until reading of 25 psi (50 in. Hg) is established in shop air supply line
secured to AFC adjusting tool.
(10) Depress test stand start button.
(11) Depress and release the fast or slow button as required until exactly 500 rpm is indicated on tachometer.
(12) Check flowmeter glass tube for air in the fuel.
Step (13) is accomplished to purge all air from the system. The gear pump must be
able to pick up fluid at 500 rpm without the aid of priming. If no fluid pickup is
indicated in the flowmeter glass tube, check the fuel filter screen for proper
installation; check that test stand FORWARD or REVERSE switch is in the
REVERSE position; check that the test stand suction control valve is open; and
check all hose connections and gear pump for condition.
If air bubbles persist, it is an indication of an air leak in the system. Turn the test
stand off and check all line connections between the test stand and fuel pump for
security, rating of gear pump to main housing and that test stand reservoir is full
(13) Work throttle lever from full open to idle several times to relieve any trapped air in pump.