2-24 PERIODIC MAINTENANCE
TEST PROCEDURE
1. Start and warm up the engine, then shut the engine off.
2. Remove the starboard side cover.
3. Remove all spark plugs.
4. Install the compression gauge into the plug hole.
! 09915-64512: Compression gauge
5. Disconnect the safety lanyard from the emergency stop
switch.
%
Disconnect the safety lanyard from the emergency stop
switch prior to cranking the engine.
This will prevent any residual fuel discharged from the
cylinders being ignited by a spark discharge from the
spark plug caps.
6. Disconnect the high pressure fuel pump lead wire.
7. Relieve the fuel line pressure. See the FUEL PRESSURE
RELIEF PROCEDURE section on the page 5-2.
CYLINDER COMPRESSION
Cylinder compression:
1300 – 1600 kPa (13 – 16 kg/cm
2
, 185 – 228 psi)
Max. difference between any other cylinders:
200 kPa (2.0 kg/cm
2
, 28 psi) or less
NOTE:
The figures shown above are guidelines only, not absolute
service limits.
Low compression pressure can indicate one or more of the
following:
• Excessively worn cylinder wall
• Worn piston or piston rings
• Stuck piston rings
• Poor seating of valves
• Ruptured or otherwise damaged cylinder head gasket
8. Disconnect the throttle rod A from the throttle control lever
B.
9. Move the throttle control lever B to full-open position and
hold it.
10. While cranking the engine with the starter motor, note the
maximum compression pressure reading on the gauge for
each cylinder.
11. Reinstall parts removed earlier.
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