Yanmar 4LHA-DTP, Operation Manual

Page: 471 / 670

Chapters Fuel Injection Equipment
8. Troubleshooting
4LHA Series
Fault
Cause
Remedy
3.
Engine's
output is
insufficient.
Defective
injection
timing, and
other failures.
(1) Knocking sounds caused by improper (too fast) injection timing.
(2) Engine overheats or emits large amount of smoke due
to improper (too slow) injection timing.
(3) Insufficient fuel delivery from feed pump.
Inspect and adjust
Inspect and adjust
Repair or replace
3.
Engine's
output is
insufficient.
Nozzle
movement
i s defective
(1) Case nut is loose.
(2) Defective injection nozzle performance.
(3) Nozzle spring is broken.
(4) Excessive oil leaks from nozzle.
Inspect and retighten
Repair or replace nozzle
Replace
Replace nozzle assembly
3.
Engine's
output is
insufficient.
Injection
pump is
defective.
(1) Max. delivery limit bolt is screwed in too far.
0 Plunger is worn.
(3) Injection amount is not uniform.
(4) Injection timings are not even.
(5) The 1st and 2nd levers of the governor and the control
rack of the injection pump are improperly lined up.
(6) Delivery stopper is loose.
(7) Delivery packing is defective.
(8) Delivery valve seat is defective.
(9) Delivery spring is broken.
Adjust
Replace
Adjust
Adjust
Repair
Inspect and retighten
Replace packing
Repair or replace
Replace
4. Idling is rough.
(1) Movement of control rack is defective.
1) Stiff plunger movement or sticking.
2) Rack and pinion fitting is defective.
3) Movement of governor is improper.
4) Delivery stopper is too tight.
(2) Uneven injection volume.
(3) Injection timing is defective.
(4) Plunger is worn and fuel injection adjustment is difficult.
(5) Governor spring is too weak.
(6) Feed pump can't feed oil at low speeds.
(7) Fuel supply is insufficient at low speeds due to clogging
of fuel filter.
Repair or replace
Repair
Repair
Inspect and adjust
Adjust
Adjust
Replace
Replace
Repair or replace
Disassemble and clean,
or replace element
5. Engine runs at high
speeds, but cuts out
at low speeds.
(1) The wire or rod of the accelerator is caught.
(2) Control rack is caught and can't be moved.
Inspect and repair
Inspect and repair
6. Engine doesn't reach
max. rpm.
(1) Governor spring is broken or excessively worn.
(2) Injection performance of nozzle is poor.
Replace
Repair or replace
7. Loud knocking.
(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.
Adjust
Adjust
Adjust
Adjust
Repair
8. Engine
emits
too much
smoke.
When exhaust
smoke is
black: (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.
Adjust
Inspect and repair
Adjust
Repair or replace
8. Engine
emits
too much
smoke.
When exhaust
smoke is
white:
(1) Injection timing is too slow.
(2) Water is mixed in fuel.
(3) Shortage of lube oil in the engine.
(4) Engine is over-cooled.
Adjust
Inspect fuel system,
and clean
Repair
Inspect
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