Yanmar 4LHA-HTP Operation Manual page 419

Chapter 3 Fuel Injection Equipment
12. Fuel Injection Nozzle
12-5 Adjusting fuel injection nozzle
12-5.1 Adjusting opening pressure (4LHA-HTE/HTZA/HTP/HTZP)
Mount the fuel injection nozzle on the nozzle tester and use
the handle to measure injection starting pressure, If it is not
at specified pressure, use the adjusting shims to increase/
decrease pressure.
Injection starting pressure
Injection starting pressure
12-5.2 Injection test
After adjusting the nozzle to the specified starting
pressure, check the fuel spray condition and seat oil
tightness.
(1) Check seat oil tightness
After two or three injections, gradually increase the
pressure up to 1.96MPa (20 kgf/cm2) before reading the
starting pressure, maintain the pressure for 5 seconds,
and make sure that no oil is dripping from the tip of the
nozzle.
Test the injection with a nozzle tester; retighten and test
again if there is excessive oil leakage from the overflow
coupling.
Replace the nozzle as a set if oil leakage is still ex-
cessive.
(2) Injection spray condition
Operate the nozzle tester lever once to twice a second
and check for abnormal injection.
1) Hole type nozzles
Replace hole type nozzles that do not satisfy the follow-
ing conditions:
• Proper spray angle (6)
• Correct injection angle (a)
• Complete atomization of fuel
• Prompt starting/stopping of injection
MPa(kgf/cm )
2
19.6-20.6 (200-210)
3-1-62
Correct
Spray from each nozzle
hole is uniform
Poor
• Excessive difference
in spray angle (9)
• Excessive difference
in injection angle (a)
• Incomplete atomization
•Sluggish starting/stopping
of injection
t4LHA Series