1998 Johnson Evinrude "EC" 150, 175 FFI Service Manual, P/N 520211, Page 20Get this manual
Synchronization and Linkage Adjustments
INote It is important that this step-by-step procedure be followed
in sequence and be performed exactly as written to ensure consistent engine idling and smooth operation throughout the RPM range
INote Remove
the throttle cable from the throttle control arm and the cable trunnion pocket before beginning this procedureThrottle Plate Synchronization
1To prevent accidental starting of engine, disconnect the spark plug leads and remove the spark plugs2Remove the air silencer assembly
3Verify that the throttle cam and cam follower are not touching
4Loosen the throttle plate link adjusting screw
5Verify all throttle plates are seatedCarefully tighten the throttle plate link adjusting screw while supporting the linkage in position6Install and adjust the throttle cable as described on Page 1-117Install the air silencer assemblyCrankshaft Position Sensor Air Gap