2007 Evinrude E-Tec 75, 90 HP outboards Service Manual, Page 204Get this manual
POWERHEAD GENERAL
GENERAL
Cylinder Compression Testing
Start and run outboard until it achieves operating temperature, then shut OFFDisconnect crankshaft position sensor (CPS) connectorRemove all spark plugsAdvance throttle linkage to WOTInstall compression tester's hose attachment into spark plug hole (14 mm threads)While cranking outboard with starter, note maximum pressure reading on gaugeRepeat procedure for each cylinderIf engine shows 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 connectorReplace spark plugsRefer to Spark Plug Indexing on p144