Yanmar 3YM20 Operation Manual page 31

3. OPERATION
NOTICE
Turn the key for a maximum of 15
seconds in the start position. If the
engine does not start the first time,
wait for about 15 seconds before
trying again. After the engine has
started, do not turn the key off. (It
should remain ON.)
Alarm devices will not work when
the key is OFF.
CAUTION
If vessel is equipped with a water
lift (water lock) muffler, excessive
cranking could cause seawater to
enter the cylinders and damage the
engine.
(4) Air Venting of the Fuel System After
Starting Failure
If the engine only idles or won't start
after several attempts, there may be
air in the fuel system. If air is in the fuel
system, fuel cannot reach the fuel in-
jection pump. Vent the air in the sys-
tem according to the following
procedures.
Fuel System Air Venting Procedures
1. Check the fuel level in the fuel tank.
Replenish if insufficient.
2. Loosen the air vent bolt at the top of
the fuel/water separator by turning it 2
or 3 times. When fuel, which does not
contain air bubbles comes out of the
bolt hole, tighten the air vent bolt.
3. Loosen the air vent bolt of the fuel filter
by turning it 2 or 3 turns.
4. Feed fuel with the fuel feed pump by
moving the lever on the left side of the
feed pump up and down.
5. Allow the fuel containing air bubbles to
flow out from the air vent bolt holes.
When the fuel coming out no longer
contains bubbles, tighten the air vent
bolt. This completes the air venting of
the fuel system. Try starting the en-
gine again.
6. In subsequent engine operation after
the start-up, the automatic air-venting
device works to purge the air in the
fuel system. No manual air-venting is
required for normal engine operation.
(5) After the engine has started
After the engine has started, check the
following items at a low engine speed:
1. Check that the gauges and alarm de-
vices on the instrument panel are nor-
mal.
2. Check for water or oil leakage from the
engine.
3. Check that exhaust color, engine vi-
brations and sound are normal.
4. When there are no problems, keep the
engine at low speed with the boat still
stopped to send lubricating oil to all
parts of the engine.
5. Check that sufficient cooling water is
discharged from the seawater outlet
pipe. Operation with inadequate sea-
water discharge will damage the im-
peller of the seawater pump. If
seawater discharge is too small, stop
the engine immediately. Identify the
cause and repair.
• Is the seacock open?
• Is the inlet strainer on the hull bottom
clogged?
• Is the seawater suction hose broken,
or does the hose suck in air due to a
loose joint?
EN
31