Power Unit; Checking The Compression Pressure; Checking The Oil Pressure - Yamaha F15B Service Manual

POWR

Power unit

Checking the compression pressure

1. Start the engine, warm it up for 5 min-
utes, and then turn it off.
2. Remove the clip from the engine stop
lanyard switch on the tiller handle or
remote control box.
3. Remove the all spark plugs, and then
install the special service tool to each
spark plug hole.
1
cC
Before removing the spark plugs, blow
compressed air in the spark plug well to
clear out any dirt or dust that may fall into
the cylinder.
Compression gauge 1:
90890-03160
4. Fully open the throttle, crank the engine
until the reading on the compression
gauge stabilizes, and then check the
compression pressure.
NOTE:
9 Do not pull the choke knob when checking
the compression pressure.
9 For remote control model. Remove the
throttle link rod and full open the throttle
lever on the carburetor by your finger, and
then measuring the minimum compression
pressure.
Minimum compression pressure
(reference data):
765 kPa (7.8 kgf/cm
5-3
Power unit
6D450010
2 , 111 psi)
5. If the measured compression pressure is
below specification, or it varies among
the cylinders, add a small amount of
engine oil to the cylinder, and check the
pressure again.
NOTE:
9 If the compression pressure increases,
check the piston and piston rings for wear.
Replace if necessary.
9 If the compression pressure does not
increase, check the valve clearance, valve,
valve seat, cylinder sleeve, cylinder head
gasket, and cylinder head. Adjust or replace
if necessary.
9 Since this outboard motor is equipped with
an automatic decompression mechanism,
accurate data may be difficult to obtain due
to differences in the way the starter rope is
pulled.

Checking the oil pressure

1. Start the engine, warm it up for 5 min-
utes, and then turn it off.
2. Remove the oil pressure switch, and then
install an oil pressure gauge 1 to the oil
pressure switch installation hole.
NOTE:
Use a pressure gauge with an adapter with a
1/8 pitch thread.
3. Check the oil pressure. Check the oil
pump, relief valve, and oil strainer if out
of specification.
Oil pressure (reference data):
330 kpa (3.36 kgf/cm
at idle speed
1
6D450020
2 , 48 psi)
6D45F11