Yanmar YM155d Service Manual page 147

1.
ENGINE AND RELATED ITEMS
n
1.
2.
3 .
Probable cause
1. No fuel.
2.
Fuel cock closed.
3. Air in fuel system.
4. Faulty delivery valve; valve clogged
5. Worn plunger.
6.
Faulty governor.
7. Sezing of nozzle.
8. lnsufficieint nozzle pressure.
9. Clogged fuel return pipe
10. Lube oil of excessively high
viscosity.
11. Low specific gravity of battery
electrolyte.
12. Faulty starter motor.
13. Faulty safety switch.
1. Unstable fuel supply:
Air in fuel system.
.
Governor linkage not functioning
smoothly.
2. Water or dust in fuel.
3.
Faulty fuel pump:
Dirt i n delivery valve.
Plunger does not function
smoothly.
Injection timing incorrect.
4. Nozzle or verge of seizing.
1. Excessive load.
2. Dirty lube oil.
Excessive viscosity.
3.
lnsufficient compression:
Worn rings, pistons, liners.
Head bolts loose.
4. Valve clearance incorrect.
5 . Overheating:
Uneven tightening or moving
components.
Insufficient coolant.
Insufficient lube oil.
6. Poor fuel oil.
Trouble
Won't start or hard
t o start
Engine starts, but
will not run
smoothly.
1
Insufficient power.
-
Remedy
Replenish fuel.
Open fuel cock.
Bleed air.
Disassemble delivery valve and clean.
Replace plunger.
Adjust governor.
Lap nozzle or replace.
Adjust injection pressure or replace nozzle.
Replace fuel pipe; i f no hole in the center of
injection pressure adjusting plate, replace.
Select lube oil suitable for ambient temperature
and engine.
charge battery.
(Refer f o section on electrical equipment)
Carrv out continuity test on safety switch
readjusting height.
Bleed air and retighten.
Adjust governor.
Replace fuel.
Clean delivery valve.
Disassemble fuel pump.
Adjust injection timing.
Lap or replace.
Reduce load.
Replace lube oil.
Replace.
Tighten.
Adjust valve clearance.
Check and adjust.
Add t o proper level.
Add t o proper level.
Replace with good quality fuel oil.