Yanmar 6LY3 series Service Manual page 167

Fuel Injection Pump / Governor / Timer
12/05
Fault
Engine output is Defective injection
insufficient. timing and other
failures.
Nozzle is defective. 1.
Injection pump is
defective.
Idling is rough.
Engine runs at high speeds but cuts out
at low speeds.
Engine doesn't reach maximum rpm.
Loud knocking.
Engine exhausts When exhaust
too much smoke. smoke is black:
When exhaust
smoke is white:
6LY3 Service Manual
Cause
1. Knocking sounds caused by improper (too
advanced) injection timing.
2. Engine overheats or emits large amounts of
smoke due to improper (too delayed) injection
timing.
3. Insufficient fuel delivery from the feed pump.
Defective injection nozzle performance.
2. Nozzle spring is broken.
3. Excessive leaks from the nozzle.
1. Plunger is worn.
2. Injection amount is not uniform.
3. Injection timings of each cylinder are not even.
4. Delivery seal is defective.
5. Delivery spring is broken.
1. Movement of the control rack is defective.
Stiff plunger movement or sticking.
2. Uneven injection volume.
3. Injection timing is defective.
4. Plunger is worn and fuel injection adjustment is
difficult.
5. Feed pump can't feed fuel at low speeds.
6. Fuel supply is insufficient at low speeds due to
clogging of the fuel filter.
1. The electric control system is defective.
2. Control rack is obstructed.
1. Governor is defective.
2. Injection nozzle spray pattern is poor.
1. Injection timing is too fast.
2. Injection from the nozzle is improper.
3. Fuel drips after each injection.
4. Uneven injection.
5. Engine overheats, or there is insufficient
compression.
1. Injection timing is too slow.
2. The amount of injection is uneven.
3. Injection from nozzle is improper.
1. Injection timing is too fast.
2. Coolant mixed with the fuel.
© 2007 Yanmar Marine International
FUEL SYSTEM
Remedy
1. Check the trouble code.
2. Check the trouble code.
3. Repair or replace.
1. Repair or replace nozzle.
2. Replace.
3. Replace the nozzle
assembly.
1. Replace.
2. Adjust.
3. Adjust.
4. Replace seal.
5. Replace.
1. Repair or replace.
2. Adjust.
3. Check the trouble code.
4. Replace.
5. Repair or replace.
6. Disassemble and clean, or
replace the element.
1. Inspect and repair.
2. Inspect and repair.
1. Check trouble code.
2. Repair or replace.
1. Check the trouble code.
2. Repair or replace the
nozzle.
3. Repair or replace the
nozzle.
4. Adjust.
5. Repair
1. Check the trouble code.
2. Adjust.
3. Repair or replace.
1. Check the trouble code.
2. Inspect the fuel system.
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