Yanmar 4LHA-HTP Operation Manual page 471

Chapters Fuel Injection Equipment
8. Troubleshooting
Fault
Defective
3. 3. 3.
injection
Engine's Engine's Engine's
timing, and
output is output is output is
other failures.
insufficient. insufficient. insufficient.
Nozzle
movement
i s defective
Injection
pump is
defective.
4. Idling is rough.
5. Engine runs at high
speeds, but cuts out
at low speeds.
6. Engine doesn't reach
max. rpm.
7. Loud knocking.
When exhaust
8. Engine 8. Engine
smoke is
emits emits
black:
too much too much
smoke. smoke.
When exhaust
smoke is
white:
(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.
(1) Case nut is loose.
(2) Defective injection nozzle performance.
(3) Nozzle spring is broken.
(4) Excessive oil leaks from nozzle.
(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.
(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.
(1) The wire or rod of the accelerator is caught.
(2) Control rack is caught and can't be moved.
(1) Governor spring is broken or excessively worn.
(2) Injection performance of nozzle is poor.
(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 of lube oil in the engine.
(4) Engine is over-cooled.
Cause
3-2-49
4LHA Series
Remedy
Inspect and adjust
Inspect and adjust
Repair or replace
Inspect and retighten
Repair or replace nozzle
Replace
Replace nozzle assembly
Adjust
Replace
Adjust
Adjust
Repair
Inspect and retighten
Replace packing
Repair or replace
Replace
Repair or replace
Repair
Repair
Inspect and adjust
Adjust
Adjust
Replace
Replace
Repair or replace
Disassemble and clean,
or replace element
Inspect and repair
Inspect and repair
Replace
Repair or replace
Adjust
Adjust
Adjust
Adjust
Repair
Adjust
Inspect and repair
Adjust
Repair or replace
Adjust
Inspect fuel system,
and clean
Repair
Inspect