Yanmar 4TNV98 Service Manual page 157

• Calculate the difference between the timing index
numbers (Figure 7-26, (1)) of the fuel injection
pump that you removed and the replacement fuel
injection pump. See Calculation Example below.
Figure 7-26
Adjusting the fuel injection timing to compensate for
the difference in pump timing index numbers:
Calculation Example
Timing Index Number
Original injection pump=
Replacement injection pump=
• If the difference between the timing index
numbers is a positive number, the fuel injection
pump mounting position must be advanced
(Figure 7-27, (2)) (rotated away from the engine)
as compared to the "standard mark" (Figure 7-27,
(1)) by the calculated positive amount, adjust the
fuel injection pump to the calculated value.
• If the difference between the timing index
numbers is a negative number, the replacement
injection pump must be retarded (Figure 7-27,
(3)) (rotated toward the engine) by the calculated
negative amount.
• Each mark on the timing sticker represents 0.5°
timing change.
4TNV98 & 4TNE98 Diesel Engine
6.8
7.3
Difference= +0.5
The above calculated difference indicates that the
replacement fuel injection pump is to be installed
at +0.5° (advanced) from the "Standard Mark"
(Figure 7-27, (1)) on the timing sticker.
In this case, rotate the top of the fuel injection
pump away from the cylinder block until the mark
on the outside upper mounting boss (Figure 7-28,
(1)) of the fuel injection pump aligns with the +0.5°
mark on the timing sticker.
Tighten the fuel injection pump mounting nuts to
specification. See Special Torque Chart on page
143.
155
Figure 7-27
Figure 7-28
Section 4. Fuel System