Re: mariner 90 inline 6 (1986)
idle mixture adjustment is a bit tricky, until you know the secret and have some patience and calm water to adjust it. Set the idle mixtures to 1-1/2 turns out from lightly seated. Launch, warm and run the motor in the lake/bay. Adjust the idle screws a bit at a time to achieve smoothest, fastest idle speed. Now try to accelerate. Normally the motor will stumble, due to being too lean. Open the top carb 1/8 turn and try to accelerate. Repeat with mid carb, and then lower carb, testing acceleration after each adjustment.