Yanmar 3YM30 Sevice Manual page 158

6. Fuel injection equipment
Fault
7. Loud knocking.
8. Engine When exhaust
exhausts smoke is
too much black:
smoke.
When exhaust
smoke is
white:
Cause
(1) Injection timing is too fast or too slow.
(2) Injection from nozzle is improper.
Fuel drips after each injection.
(3) Injection nozzle starting pressure is too high
(4) Uneven injection.
(5) Engine overheats, or insufficient
compression.
(1) Injection timing is too fast.
(2) Air volume intake is insufficient.
(3) The amount of injection is uneven.
(4) Injection from nozzle is improper.
(1) Injection timing is too slow.
(2) Water is mixed in fuel.
(3) Shortage or lube oil in the engine.
(4) Engine is over-cooled.
143
Remedy
Adjust
Adjust
Adjust
Adjust
Repair
Adjust
Inspect and repair
Adjust
Repair or replace
Adjust
Inspect fuel system, and
clean
Repair
Inspect