Stalling Problems 1985 90hp Merc

[bluecamo]

I am having problems keeping my 90hp Mercury Outboard started with a load. When I run it with muffs out of the water, I can crank it up with do whatever with out any problems. When I put it in the water I could not put the motor into forward or reverse without it stalling out. I would compare it to a small engine that has the choke on, as soon as you put it in gear it stalls out. I have been having some problems actually getting the engine to fire. Once it does out of there water and with muffs, there are usually no issues. The problems seem to be happening with a load. Even just letting it idle will usually stall out eventually when in the water.

When I bought the boat about a month ago it tested really good on the compression checks, 135 range. The boat had not been used in 2 years though. Is there anything i should check for initially?

From everything I have been reading, it seems like spark plugs and carbs seem to be the normal issues with stalling out in the water.

Thanks for the help.

 

[blue90HP50]

Re: Stalling Problems 1985 90hp Merc

This is what I would do: Install new plugs. Back Idle mixture screws out (CCW) 1/8th turn. Back Down ramp til motor is immersed to operating depth,trim to level, and try to get her to idle on the ramp. If it won't idle, turn screw 1/8th turn more CCW and try it. If still won't idle, post back and the experts will help. Fresh fuel?
Unfortunately, you may need to re-build carbs and replace fuel lines. My 2 cents opinion based on my reviving my 82 90 HP.
Good Luck
Blue

 

[bluecamo]

Re: Stalling Problems 1985 90hp Merc

Thank you for your help! I am a newbie and am not too familiar with outboards. Everything I keep reading seems to lead to new fuel lines and carbs. I will try your suggestion first.

 

[Chris1956]

Re: Stalling Problems 1985 90hp Merc

You either have idle mixture too lean(as Blue implies), or dirty carbs or both. You can try to open the carb idle mixture screw 1/8 of a turn, however, if the carbs are dirty, this will fail also.