I've got a 1987 200hp V6 Ocean Runner with a 1994 225 Powerhead on it. On the port side of the motor, right behind the air cover is a black thing with a red arrow (adjustable) on it. There appears to be fuel lines and two wires - one black, one purple w/white. Don't see it in the manual. Turning the red dial makes the engine run different. I returned it to it's original mark, just wondering if I should make any adjustments since I just did a tune up. Thanks for the help.