1983 Mercury 90 hp Throttle problem

[mrduck]

I have a 1983 Mercury 90 hp, inline six. It starts fine, idles fine, but when I throttle up in falls on its face. I have rebuilt the carburetors, adjusted the low speed jet a turn and a half out to get it to idle correctly. I enriched the low speed out to 2 - 2 1/2 but When I throttle up it falls. Any ideas?

 

[Chris1956]

Re: 1983 Mercury 90 hp Throttle problem

Sounds like your idle mixture is still not correct. Set the carbs back to 1-1/2 turns out and take the boat out and under load, engine warm, do a trial and error idle mixture setting.

Remember the top carb runs a bit leaner than the mid carb. The mid carb runs a bit leaner than the bottom carb. So it is likely the top carb needs to be set richest, and the mid carb richer than the bottom carb.

So when she stumbles on acceleration, open the top carb 1/8 turn. Repeat with mid carb and bottom carb, testing after each adjustment. Then repeat, starting with top carb again.

 

[mrduck]

Re: 1983 Mercury 90 hp Throttle problem

Sounds like your idle mixture is still not correct. Set the carbs back to 1-1/2 turns out and take the boat out and under load, engine warm, do a trial and error idle mixture setting.

Remember the top carb runs a bit leaner than the mid carb. The mid carb runs a bit leaner than the bottom carb. So it is likely the top carb needs to be set richest, and the mid carb richer than the bottom carb.

So when she stumbles on acceleration, open the top carb 1/8 turn. Repeat with mid carb and bottom carb, testing after each adjustment. Then repeat, starting with top carb again.

Thanks Chris, I haven't done the latter part of your post, I will try it.