TM 9-2320-260-34-1
5-25. FUEL PUMP CALIBRATION (Contd)
NOTE
Once 8 in. (20.3 cm) HG vacuum has been obtained, do not change
setting on test stand. Readings will fluctuate during other tests.
Record increases or decreases as they occur.
3. Adjust flow control valve (11) to obtain 8 in. (20.3 cm) HG mercury on vacuum gage (3).
4. Place selector valve (10) in rotameter position.
5. Increase fuel pump (4) speed until fuel pressure drops. Test stand tachometer (2) should read
between 2130-2150 rpm. If tachometer reading is not within limits, strip test stand (1).
WARNING
Test stand must be shutoff before changing shims in spring pack.
Small parts under pressure may shoot out causing injury to
personnel or damage to equipment.
NOTE
Perform steps 6 through 10 only if spring pack shims are to be
changed.
Each 0.001 in. (0.025 mm) shim thickness will change speed
approximately two rpm. Shims are available in 0.005, 0.010, and
0.020 in. (0.13, 0.25, and 0.51 mm) thickness.
If more than .015 in. (0.38 mm) thick shim is required, replace
spring.
6. Remove fuel pump (4) from test stand (1) (para. 5-24).
7. If cutoff is too low, remove spring pack (15) (para. 5-18) and add shims.
8. If cutoff is too high, remove spring pack (15) (para. 5-18) and remove shims.
9. Install fuel pump (4) on test stand (1) (para. 5-24).
10. Run fuel pump (4) at 500 rpm. Move throttle lever (12) back and forth until rotameter shows no air
in fuel. Recheck governor cutoff rpm.
5-75
