Komatsu 4D98 Series - Fuel Injection Timing Inspection and Adjustment

3. Inspection and Adjustement
3.7
1)
2)
3)
4)
5)
6)
7)
8)
9)
Fuel Injection Timing Inspection and Adjustment
Set the engine ready for starting.
(Complete air bleeding from the fuel
line.)
See that the fuel injection timing check
mark on the fuel pump mounting flange
and gear case are aligned.
Set the control valve at the operating
position.
Disconnect the high pressure tube for
the No.1 cylinder on the fuel pump side.
(Do not remove the delivery valve.)
Check fuel discharge from the delivery
holder while turning the crankshaft
(clockwise as seen from the radiator),
and stop turning it when the fuel comes
out.
Check the crankshaft pullet top mark
position on the timing scale. The No.1
piston can be checked at its top dead
center when the position is between 10’
before the. top (10 graduations on the
left from 0) and 10’ after the top.
Fuel inject& pump
mounting nut
Fuel injection timing
1
in
:in
ijec-
iing
)nal
m
Crankshaft pulley
Then wipe the outlet of the delivery holder clean. Turn the crankshaft in the opposite direction
to return to approx. 20” before the top.
Slowly turn the crankshaft clockwise. As the oil surface in the deliver holder rises, stop rota-
tion upon rising and check the position on the timing scale. The injection timing is normal if the
top mark is positioned in the timing scale range shown in the table below on the left side from
0.
4TNE94=98
Standard: Degrees bTDC (FID)
10-12
Repeat steps 6) to 8) a few times.
4TNE106
4TNE106T
13-15 11-13
(Note)
Injection timing check for one cylinder is generally sufficient. If it is to be checked for all four
cylinders, turn the crankshaft 180” each time and check in the order of cylinders No.1, No.3,
No.4, No.2 and No.1. (The No.1 cylinder is positioned furthest from the radiator.)
The cylinder to be checked is not limited to the No.1 cylinder but any desired one may be
checked.
If the ignition timing is outside the standard, loosen the fuel pump mounting nut and rotate the
fuel pump toward or away from the engine for adjustment. Rotate toward the engine to ad-
vance the timing, and away from the engine to delay the timing.
(One graduation on the gear case scale corresponds to one degree in ignition timing.)
10)
3-8