PERIODIC MAINTENANCE
Periodic Maintenance Procedures
12/05
6LY3 Service Manual
4-29
© 2007 Yanmar Marine International
Replace every 2,000 hours or 2 years of engine
operation, whichever comes first.
• Overhaul and Check the Fuel Feed Pump
• Clean the Engine Oil Cooler
• Clean the Seawater and Freshwater Systems
• Replace the Rubber Fuel Hoses
• Replace the Thermostat
Overhaul and Check the Fuel Feed Pump
The fuel injection pump must be overhauled and
checked to ensure optimal engine performance.
Disassembly of the Fuel Injection Pump
1. Remove the piston spring stopper plug and pull
out the piston and piston spring.
2. Remove the snap ring and pull out the tappet
assembly.
3. Pull out the inter-spindle.
4. Remove the priming pump.
5. Remove the discharge valve spring stopper and
remove the valve and spring from inside.
6. Remove the O-ring.
Inspecting the Fuel Injection Pump
Figure 4-35
Figure 4-35
1 – Air Inlet Pressure
2 – Container Filled w / Light Oil
3 – Blocked
4 – Tappet
5 – Measuring Cylinder
1. Block the priming pump with your finger and
check whether the pressed-in piston returns by
spring force. If the piston returns, the piston
does not have enough negative (-) pressure.
Replace the priming pump as a set.
2. Check the piston spring for cuts, cracks, uneven
wear and rust.
3. If the piston, inter-spindle or tappet assembly is
extremely worn, replace the part.
4. Check the contact surface of the valve and
valve seat for defects.
5. If there is play in a valve seat, which has been
cemented into the feed pump body, the whole
fuel pump body must be replaced.
See Fuel Injection Pump / Governor / Timer on
page 6-7
for the procedure of adjustment.
NOTICE: Play in the valve seat hinders the opening
and closing of the valve, causing insufficient fuel
supply and abnormal wear of the tappets and
camshaft.
Assemble the Fuel Feed Pump
1. Install the O-ring.
2. Install the discharge valve spring stopper and
install the valve and spring from inside.
3. Install the priming pump.
4. Push in the inter-spindle.
5. Install the snap ring and push in the tappet
assembly.
6. Install the piston spring stopper plug and push
in the piston and piston and piston spring.
Every 2000 Hours of Operation
0006191
(5)
(1)
(2)
(4)
(
3
)
