TRUCK SERVICE MANUAL
6. If flow value cannot be obtained and held, check idle
plunger (button) and governor break. The difference
between plungers is about 5 to 10 psi. Be certain
adapter, Part No. 144676, is used with plungers code
170 and over. Inspect pulsation damper diaphragm.
7. 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 speed indicated by "Governor Cut-Off
RPM". For example' 2130/2150 rpm on 2100 rpm pump.
Fig. 5-1-16.
8. If speed is lower than specified, add shims between
governor spring and retainer. Check Table 5-1-2 for
spring specifications. To reduce speed, remove shims.
Each 0.001 inch shim thickness will change speed
Fig. 5-1-18, F5240. Comparison of fuel pump springs
approximately 2 rpm on NH Engines. Fig. 5-1-17,
Shims are available in 0.005, 0.007, 0.010 and 0.020
inch [0.13, 0.18, 0.25 and 0.51 mm] .
Set Throttle Leakage Standard Automotive Governor
Note: When pump is opened to make adjustments, open
Note: Make sure fuel is up to temperature when setting
main control valve to flow-meter wide open and move
throttle leakage.
throttle lever back and forth until flow-meter shows no
air, so air may be expelled more rapidly from system.
1. Make throttle leakage setting on pumps with front
After air is expelled, reset flow-meter flow as outlined in
"Set Pump Flow."
throttle screw fully open.
2. Move throttle toward gear pump and hold firmly
against. stop.
3. Open leakage valve at end of orifice block wide open,
close main-flow and idle valves.
4. Run test stand speed up to pump rated speed.
5. With 200 cc graduate check fuel delivery for one
minute. Do not keep at this setting any longer than
absolutely necessary. Fig. 5-1-19.
6. CC delivery should be as specified by "Throttle
Leakage" in the calibration data. If not to specifications,
screw front Fig. 5-1-16, F5108. Check governor cut off
Fig. 5-1-16, F5108. Check governor cut off speed.
speed.
Fig. 5-1-19, F5111. Measure throttle leakage
Fig. 5-1-17. F5109, Shim governor spring
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