lines.
To check the pump, disconnect the pump lines from the vacuum and pressure fuel
filter sumps and connect these lines to the altimeter and fuel pressure instruments respec-
tively. Refer to figure 3-2 for the vacuum and pressure lines schematic diagram. Turn on
the motor and check that 29 inches of vacuum is produced on the vacuum side of the pump
and that a minimum of 25 pounds of pressure is produced on the pressure side. If the pump
produces insufficient vacuum or pressure, the pump is defective and should be replaced.
If the pump is capable of proper operation then a leak exists elsewhere in the test set. All
fittings, gaskets, lines, and components should be checked for leaks and defective com-
ponents replaced.
If replacing a check valve, be sure to orient replacement valve with
arrow pointing in same direction as arrow on original valve.
3-11.
Faults in the electrical system can be found by performing a point-to-point wiring
check. Refer to figure 3-3 for the schematic and wiring diagram of the test set.
3-12. PARTS REPLACEMENT.
3-13. Mechanical and electrical components of the test set are replaced using standard shop
techniques. Figure 3-2 identifies the components, flexible hoses and rigid tubing used in the
test set. When replacing check valves, it is essential that the replacement valve be oriented
with its arrow pointing in the same direction as the arrow on the original valve. When re-
placing diode rectifiers, it is also essential that the replacement diode be installed with the
same orientation as the diode which it replaces.
Failure to observe these check valve and
diode replacement instructions will result in an inoperative test set.
3-14. INSTRUMENT REPLACEMENT.
3-15. The five indicating instruments of the test set are AN or MIL standard parts which
can be obtained through normal supply channels.
They are readily replaced by disconnect-
ing the rear fitting hose, removing the instrument from the test set panel, installing the
new instrument, and reconnecting the hose fitting. Care should be exercised in reconnecting
3-6