Yanmar 4LHA-HTP Operation Manual page 456

Chapter 3 Fuel Injection Equipment
4. Adjustment of Fuel Injection Pump and Governor
4-4 Plunger pressure test
(1) Mount the pressure gauge to the delivery retainer
of the cylinder to be t e s t e d .
Max. pressure gauge reading
Connecting screw dimensions
(2) Set the governor control lever in the stop position,
operate the injection pump at about 200 rpm, and
make sure that the pressure gauge reading is
49.0(500)MPa(kgf/cm) or more. All the time lightly
move the control rack towards full throttle (drive
side).
Replace the plunger if the pressure does not reach
this value.
(3) Immediately release the rack after the pressure has
stopped injection.
A t the same time, check to see that oil is not leak-
ing from the delivery retainer or fuel injection
piping, and that there is no extreme drop in pres-
sure.
4-5 Delivery valve pressure test
(1) Perform the plunger pressure test in the same way,
bringing the pressure to about 11.8(120)/MPa
(kgf/cm), and then stopping injection.
(2) After the pressure has risen to the above value,
measure the time it takes to drop from 9.81 - 8.83
(100 - 90) MPa (kgf/cm).
98.1(1,000)
MPa(kgf/cm)
M12x 1.5
Pressure gauge
3-2-34
9.81~8.83(100-.90)
MPa(kgf/cm)
If the pressure drops faster than this, wash the
delivery valve, and retest. Replace the delivery
valve if the pressure continues to drop rapidly.
4-6 Adjusting injection volume
(uniformity of each cylinder)
The injection volume is determined by the fuel injec-
tion pump rpm and rack position. Check and adjust to
bring it to the specified value.
4-6.1 Measuring injection volume
(1) Preparation
Set the pump rpm, rack position and measuring
stroke to the specified value and measure:
Pump RPM
Pump rotating direction
Rack indicator scale
reading
(2) Measuring injection volume
Measure the injection volume
stroke, and adjust as follows if it is not within the
specified value.
Measuring stroke
Specified injection volume
at standard rack position
Nonuniformity of cylinders
4-62 Adjustment of injection volume
(1) Adjustment of injection volume: loosen the two
nuts on the flange of the plunger barrel, and turn
the plunger barrel to the right o r left.
(2) Measure the injection volume of each cylinder
again.
Repeat this process until the injection volume for
every cylinder is the same, (within the specified
limit)
(3) After completing the
the nuts of plunger barrel flange.
Tightening torque
(4) If not aligned with the match mark, make a new
match mark.
4LHA Series
5 seconds
(to drop 0.98(10)MPa(kgf/cm')
See separate service data
Right looking from drive side
See separate service data
at the standard
See injection pump
service data
measurements, retighten
25.5-27.5(2.6-2.8)N(kgf) m