B3.9 and B5.9 Series Engines
Fuel Pump Back Leakage Valve (005-059)
Section 5 - Fuel System - Group 05
Speed Droop Adjustment
NOTE: If serious surging occurs during the warm-up pe-
riod, turn the speed droop adjusting screw clockwise until
the surging stops.
NOTE: When the speed droop adjustments are made, it is
necessary to adjust the throttle position.
Adjust the governor as follows:
1. Operate the engine until normal operating tempera-
ture is obtained 91°C [195°F].
2. When the engine reaches operating temperature, po-
sition the throttle to attain rated speed, and apply 100-
percent load. Adjust the throttle position as necessary
to obtain 100 percent performance.
3. Remove the load, and check for the specified no-load
If the no-load speed is incorrect, loosen the locking
cap, and adjust the speed droop adjusting screw
(clockwise for increased droop, counterclockwise
for less droop). If surging occurs when the load is
removed, turn the adjusting cap clockwise to elimi-
nate the surge. Tighten the locking cap to secure the
4. Check the 100-percent load and no-load performance
again, and make adjustments as necessary.
Fuel Pump Back Leakage Valve
Disconnect the high-pressure line. Refer to Procedure 006-
NOTE: Because the valves are installed 90 degrees to the
pump axis, the pump will possibly need to be removed to
change the valves close to the cylinder block.
Remove the valve.