Yanmar 3JH4E Service Manual page 138

3. Troubleshooting
Malfunctions
The engine exhaust contains
smoke and the engine "knocks".
The engine output is unstable.
Insufficient output.
1. The injection quantity is
insufficient
2. The injection timing is too
advanced and the engine is
"knocking".
3. The injection timing is too
retarded and the engine is
overheating or the exhaust
contains smoke.
Causes
1. The injection timing is incorrect.
2. The nozzle or nozzle holder is
functioning incorrectly.
3. The injection quantity is
excessive.
1. The fuel filter element is
clogged and fuel oil delivery is
poor.
2. The amount of fuel or pressure
delivered by the feed pump is
too little.
3. The injection pump is sucking
air.
4. The regulating valve is stuck in
the open position.
5. The plunger is sticking and
does not travel its full stroke.
6. The plunger spring is broken.
7. The control sleeve is not
sliding smoothly.
8. The governor lever is not
operating properly or is worn
excessively.
9. The delivery valve spring is
broken.
10. The delivery valve is not
sliding properly.
11. The nozzle or the nozzle
holder is not functioning
properly.
12. The injection timing is
incorrect.
1. The specified full-load injection
quantity is not delivered.
2. The control lever is not reaching
the maximum speed position.
3. The governor spring is weak
and therefore the governed
speed is too low.
4. The plunger is worn.
5. The delivery valve seating
portions are damaged.
118
Remedies
Readjust the timing.
Inspect, then repair or replace.
Readjust.
Clean or replace.
Inspect and repair.
Inspect and repair.
Replace.
Replace the distributor assembly.
Replace.
Repair or replace.
Repair or replace
Replace.
Repair or replace.
Inspect, and then repair or replace.
Readjust.
Readjust.
Readjust.
Replace.
Replace the distributor assembly.
Replace.
Readjust.
Readjust.