B3.9 and B5.9 Series Engines
Fuel Pump Idle Speed (005-029)
Section 5 - Fuel System - Group 05
Stanadyne DB4 Fuel Injection Pump Adjustment Screw
The low-idle adjustment screw on the DB4 fuel injection
pump is mounted on the control lever assembly. The ad-
justment screw can be used to increase the idle speed to
compensate for accessory loading. The low-idle adjust-
ment screw must be adjusted by an authorized service
dealer and resealed.
NOTE: Never turn the idle adjusting screw out (reduce idle
speed) on the speed drop governor-equipped fuel injection
pump; this can result in disengagement of the throttle lever
from the guide bushing.
The high-idle adjustment screw (A) is sealed. The adjust-
ment screw on the DB4 fuel injection pump is mounted on
the control lever assembly. The high-idle adjustment screw
must be adjusted by an authorized service dealer.
The speed droop adjustment screw (B) is located above the
delivery head. The fuel pump governor sensitivity can be
adjusted to increase or decrease governor regulation.
Lucas CAV DPA/DPS Fuel Injection Pump Adjustment
The idle adjustment screw provides a stop for the lever at
low speed. The adjustment screw can be used to increase
idle speed for accessory loading, or, if required, to lower the
idle speed. The high-idle screw is sealed and must be
adjusted by an authorized repair shop, and then resealed.
A - Idle screw
B - High-idle screw