2003 ST 4 Stroke 9.9/15HP Johnson outboards Service Manual, Page 35Get this manual
PERIODIC MAINTENANCE
CARBURETOR
4Install the timing belt on the timing pulley first, then the cam pulleyIACAUTION
Cam pulley PUNCH mark
Always keep the timing belt away from grease and oilIACAUTION
The timing belt must be installed with the arrow mark on the timing belt toward the direction of rotation