FUEL SYSTEM
Fuel Injection Pump / Governor / Timer
12/05
6LY3 Service Manual
6-25
© 2007 Yanmar Marine International
Engine output is
insufficient.
Defective injection
timing and other
failures.
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.
1. Check the trouble code.
2. Check the trouble code.
3. Repair or replace.
Nozzle is defective. 1. Defective injection nozzle performance.
2. Nozzle spring is broken.
3. Excessive leaks from the nozzle.
1. Repair or replace nozzle.
2. Replace.
3. Replace the nozzle
assembly.
Injection pump is
defective.
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. Replace.
2. Adjust.
3. Adjust.
4. Replace seal.
5. Replace.
Idling is rough.
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. Repair or replace.
2. Adjust.
3. Check the trouble code.
4. Replace.
5. Repair or replace.
6. Disassemble and clean, or
replace the element.
Engine runs at high speeds but cuts out
at low speeds.
1. The electric control system is defective.
2. Control rack is obstructed.
1. Inspect and repair.
2. Inspect and repair.
Engine doesn’t reach maximum rpm.
1. Governor is defective.
2. Injection nozzle spray pattern is poor.
1. Check trouble code.
2. Repair or replace.
Loud knocking.
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. Check the trouble code.
2. Repair or replace the
nozzle.
3. Repair or replace the
nozzle.
4. Adjust.
5. Repair
Engine exhausts
too much smoke.
When exhaust
smoke is black:
1. Injection timing is too slow.
2. The amount of injection is uneven.
3. Injection from nozzle is improper.
1. Check the trouble code.
2. Adjust.
3. Repair or replace.
When exhaust
smoke is white:
1. Injection timing is too fast.
2. Coolant mixed with the fuel.
1. Check the trouble code.
2. Inspect the fuel system.
Fault
Cause
Remedy