Low Idle Mixture question..

[*WEAVER*]

I have a 1990 90 horse 3 cylinder Mercury, I had to take the carbs off and clean them. Unfortunately I forgot to count how many turns my low idle mixture screws were set at on the 3 carbs. I went ahead and set it at the 1 1/2 turns out from lightly seated that is recommended on this motor. The motor idles good, but I want to make sure when I take it out on the water that I have the correct settings on those. Do you guys have a recommended way of adjusting these to the correct settings?

Thanks

 

[ENSIGN]

Re: Low Idle Mixture question..

One& a half turns is a good start.Put the boat in the water and run it.If it seems ok just adjust the idle speed.You don't want to lean out your mixture adjustments to get a real smooth idle as this will make it hard to start and can lead to internal problmens. Hope this helps,Ted

 

[Silvertip]

Re: Low Idle Mixture question..

The 1-1/2 turn out from lightly seated is just a starting point for that adjustment. There is no one setting fits all. With the engine in the water (not on muffs) turn the idle mixture screw inward in 1/8 turn increments, pausing for 10 - 15 seconds after each adjustment. When the engine just begins to run more roughly, note the position of the screwdriver slot and then turn the screw the other direction (out) again in 1/8 increments carefully noting the slot position, until the engine again runs rough. Set the screw at the 1/2 point between the two settings. Reset idle speed after doing each carb. Repeat this on the other carbs and reset idle speed to spec. You may want to repeat the process to ensure you have the setting optimized for idle speed. You now need to do a hole shot test where you put the engine in gear and go full throttle. If the engine bogs because of a slightly rich or lean condition, give each screw 1/8 turn in or out to cure the bog. You will generally need to go a bit richer (out) on each screw.