Yanmar 4LHA-DTP, Operation Manual

Page: 469 / 670

Chapter 3 Fuel Injection Equipment
7. Fuel Injection Nozzle
4LHA Seriei
7-6.2 Injection t e s t
After adjusting the nozzle to the specified starting
pressure, check the fuel spray condition and seat oil
tightness.
(1) Checking t h e seat oil tightness
After two o r three injections, gradually increase
the pressure up to 1.96 (20) MPa (kgf/cm). Before
reading the starting pressure, maintain the pressure
for 5 seconds and make sure that no oil is dripping
from the t i p o f the nozzle.
Test the injection with a nozzle tester, retighten
and test a g a i n 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 s p r a y condition
Operate the nozzle tester lever once or twice a
second and check for abnormal injection.
1) Hole type nozzles
Replace hole type nozzles that do not satisfy the
following conditions:
. Proper spray angle {8)
• Correct injection angle (a)
• Complete atomization of fuel
• Prompt starting/stopping of injection
Spray from each nozzle
hole is uniform
Poor
.TL
• Excessive difference
in spray angle (9)
• Excessive difference
in injection angle (a)
• Incomplete atomization
•Sluggish starting/stopping
of injection
3-2-47