Yanmar 4TNV98, Service Manual

Page: 167 / 246

4TNV98 & 4TNE98 Diesel Engine Section 4. Fuel System 165
6. Pump the operating lever more rapidly to
repeatedly “pop” the injector and observe the
spray pattern. The pattern should be a very fine
uniform spray
(Figure 7-50) . If a dripping or an
uneven pattern is seen (Figure 7-51) , service or
replace the injector.
Figure 7-50
Figure7-51
If the fuel injector fails any of these tests, it should
be serviced or replaced as necessary. If the
pressure is outside specified limits, adjust the
pressure. See Adjusting Fuel Injector Pressure on
page 166.
Disassembly and Inspection of Fuel
Injectors
CAUTION
Never use a steel wire brush to clean fuel
injectors. Damage to the nozzle and other
components is likely to result.
1. Clean carbon from used injectors using clean
diesel fuel. Hardened deposits or varnish can be
cleaned using a brass wire brush.
Figure 7-52
(1) Fuel Return Passage. (2) Injector ID Location.
(3) Injector Body. (4) Pressure Adjusting Shims. (5) Spring.
(6) Spring Seat. (7) Valve Stop Spacer. (8) Nozzle Valve.
(9) Nozzle Body. (10) Nozzle Case Nut
2. Place the fuel injector in a soft-jawed vise with
the nozzle pointing up.
3. Remove the nozzle case nut.
4.
Carefully remove the injector from the vise.