TM 5-2420-230-24-2
Speed Droop Governor (005-058)
B3.9 and B5.9 Series Engines
Page 5-94
Section 5 - Fuel System - Group 05
Use a multimeter to perform a continuity check between
port A of the metro-pack connector and the fuel pump
shutdown solenoid connector.
Repair the wire if there is an open circuit.
(Spec = Less than 10 ohms).
Speed Droop Governor (005-058)
Adjust (005-058-029)
Stanadyne DB4 (Generator Application) Speed Droop
Governor
Governor regulation of 3 percent to 5 percent can be at-
tained with the speed droop governor. Precise control of
governor regulation is done by decreasing or increasing
the effective length of the governor control spring; this also
decreases or increases the spring control spring rate. The
governor control spring is threaded into an adjusting cap
assembly and is referred to as the control rod assembly. By
turning the adjusting cap in the clockwise direction, as
viewed from the fuel transfer pump end, the control rod
spring shortens and becomes less sensitive, thereby in-
creasing governor regulation. Turning the adjusting cap in
the counterclockwise direction increases the control rod
spring length and sensitivity, which will decrease governor
regulation.
The external speed droop adjustment screw, located at the
rear of the fuel injection pump housing, controls the gov-
ernor sensitivity. The droop screw adjustment varies the
governor regulation by changing the effective spring rate.
This adjustment will affect both full-load and no-load fre-
quency settings and can require the high-speed stop screw
be reset.
Speed droop adjustments must be made while the engine
is operating. After each adjustment of the droop screw, the
engine must be shutdown briefly in order to allow the
governor spring to unload and the adjusting mechanism to
seek its final position in the spring. Turning the screw in
shortens the control spring, making it less sensitive and
increasing speed droop. Turning the adjusting screw out
has the opposite effect. Speed droop is the fuel injection
pump's ability to respond to changing engine loads.
L-954