1999 15 HP Merc manual start tiller handle. Carb was leaking gas so I rebuilt it figuring it was the needle. Also changed plugs. Went to tune it today and couldn't get it going. It pulls fine and will sputter for 2-3 seconds like it is going to start, but then dies out. Gas is new, correctly mixed, fuel line and bulb are new. I backed the low speed idle screw out the recommended 1-2 turns and made many adjustments with it to no avail. Idle speed knob position doesn't have any effect on this either, but pulling the choke will kill it right away. After 5 pulls or so in rapid succession I can hear a high pitched sound like compressed air escaping from somewhere. Any thoughts?
