[lazydawg]

I have a 1989 40Hp Mariner. It runs well at full speed and idles at stop fine, but it will not idle in forward. The motor just shuts off. It is a recent purchase (3 months) and the carbs were rebuilt professionally before I bought it. What should my first step be?

[lazydawg]

^

[sharkcat]

Your first step should be get a manual.I would then check float levels/needle & seats,reassemble,do a link & synch,then adjust idle mixture screws with the engine running in gear in the water.The problem you have could be the idle speed is too slow/the carbs are out of synch with the ignition/the mixture is too lean.Doing the above will fix it.Hope this helps

[lazydawg]

I am new to outboards so pardon my ignorance. What do you mean by link & synch? I do have a manual that has already proven very useful. Thanks for the help.

[lazydawg]

I should also add that it will usually crank right back up, but if you ease it into forward it shuts off. If you quickly go into forward and give it some throttle it will run fine until you back the speed down toward idle.

[sharkcat]

Hi lazydawg a link & synch means adjust the ignition stops so the timing is right at idle & WOT,adjust the throttle stops so the carb butterflies are closed at idle & fully open at WOT,then synchronize the linkages so the ignition advances at the right time when you open the throttle.Your manual should have a section on adjusting linkages etc.Before you do this check the float levels & needles so you know they are right.If they are too high it can cause flooding at idle & too low can make the engine run lean not good for a two stroke.I know you say the carbs were rebuilt professionally before you bought the motor/boat...but rule #1 never assume anything.I had professionally rebuilt motor on my boat when i bought it.The link & synch was out,the float levels all over the place etc..So check it yourself that way you know its right

[Reelistic]

I once owned an 83 70hp merc and experienced the same problem. My fix was to replace the stator... the low speed windings went T.U. Look in a service manual for the proper resistance readings for your stator.

[Blacksheep312]

Hi, I have the same motor. I just need to pick up the idle a bit. Can you help me find the screw that will add more idle. Pictures would be nice too if possible. E-mail meblacksheep312@cox.net