197
Powerhead
Compression Testing
10
Compression Testing
Start and run outboard until it achieves operating
temperature, then shut OFF.
Disconnect crankshaft position sensor (CPS) con-
nector. Remove all spark plugs.
Advance throttle linkage to WOT.
Install compression tester’s hose attachment into
spark plug hole (14 mm threads).
While cranking outboard with starter, note maxi-
mum pressure reading on gauge. Repeat proce-
dure for each cylinder.
If engine shows a variation greater than 15 psi
(100 kPa) between cylinders, check for:
• damaged cylinder head
• damaged pistons
• broken or stuck piston rings
• scored cylinder walls
Return throttle to idle position and reconnect CPS
connector. Replace spark plugs. Refer to Spark
Plug Indexing on p. 43.
Powerhead Removal
2-Cylinder Models
Remove lower motor covers. Refer to Lower
Cover Removal on p. 56.
Disconnect power trim connectors and exhaust
water valve electrical connector (60 HP, 2-cylinder
models).
Disconnect cooling water hoses from exhaust
housing.
WARNING
Protect against hazardous fuel spray. Before
starting any fuel system service, carefully
relieve fuel system pressure. Refer to Reliev-
ing Fuel System Pressure on p. 168.
Disconnect the Crankshaft Position Sensor
(CPS) to prevent accidental starting while
servicing.
1. Connectors
008429
1. Overboard indicator hose
2. Drain hose
004298
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