Yanmar 6LY3 series Service Manual page 310

TROUBLESHOOTING
Trouble symptom
Insufficient engine output.
(Reduced maximum engine speed, reduced boat speed.)
Engine is overloaded.
Reduction of maximum
speed is not because of
output reduction.
Faulty fuel injection nozzle.
Insufficient fuel supply.
Insufficient intake air volume. Clogged air cleaner.
Faulty combustion because
of blow-by and reduced air
compression pressure.
13-20
Causes
Increased ship resistance
Excessive burden.
Faulty valve and / or seat.
Sticking valve.
Wear of seat.
Clogged fuel injection
hole(s).
Decrease in fuel opening
pressure.
The fuel tank valve is not
opening sufficiently.
Clogged fuel filter.
Faulty fuel feed pump.
Wear of the fuel injection
pump plunger.
Decrease in intake air
pressure.
Intake air temperature is too
high.
Clogged exhaust gas
passage.
Faulty ventilation in the
engine room.
No valve clearance.
Faulty contact between valve
and seat.
Seized main moving parts.
Wear of piston ring.
Sticking piston ring.
© 2007 Yanmar Marine International
Troubleshooting by Symptom
Corrective action
Check around the propeller
and boat hull. Check the
deadweight of the boat.
Check the fuel spray
condition with a tester. If a
malfunction is found, send it
to the FIE shop for service or
replacement.
Open the fuel tank valve
fully.
Replace the fuel filter.
Disassemble and service.
Ask the FIE shop for
maintenance.
Clean or replace.
Check the turbocharger.
Clean the blower of
turbocharger.
Check the impeller of the
seawater pump. Check for a
clogged seawater line and
for dirt in the intercooler core.
Check the exhaust passage. See Inspecting Intake /
Check the ventilation unit.
Adjust the valve clearance.
Lap the valve or replace.
Disassemble and check.
Replace if necessary.
Check and replace if
necessary.
Check and clean or replace.
6LY3 Service Manual
Remarks
—
See Fuel Injection Nozzle
Components and Functions
on page 6-26.
See Handling Diesel Fuel on
page 3-7.
See Fuel Filter Components
and Functions on page 6-33.
See Fuel Feed Pump
Components and Functions
on page 6-28.
See Fuel Injection Pump /
Governor / Timer on
page 6-7.
See Troubleshooting the
Fuel Injection System on
page 6-24.
See Turbocharger
Components and Functions
on page 9-4.
See Seawater Pump
Components and Functions
on page 7-6.
Exhaust Valves and Valve
Guides on page 5-30.
—
See Service Standards on
page 14-3.
See Service Standards on
page 14-3.
See Engine on page 5-1.
See Measuring the Piston
Rings on page 5-38.
See Measuring the Piston
Rings on page 5-38.