TM 10-3950-672-24-2
Injection Pump Timing
Pump-to-engine timing is extremely critical. Pump timing that is off by only a few crankshaft degrees will cause:
1. Poor performance -- starting and power
2. Excessive smoke and emissions
3. Poor fuel economy
Engine pump timing begins with the timing of the
injection pump drive gear to the camshaft gear.
The first step is the location of TDC for Cylinder Number
1.
Then, depending on the engine configuration, a letter on
the gear is aligned with the mark on the camshaft gear.
Letter
Engine
A
4B3.9, 4BT3.9 (Lucas CAV DPA Pump)
To verify that the injection pump is timed correctly, first
check the alignment marks on the pump flange and gear
housing.
Note: 1 mm of rotation past the timing mark will
advance or retard (depending on direction of
rotation) the pump timing by 1 degree.
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