Mercury 200 20 hp outboard hard to start and slips

[kenlogsdon]

Folks, I am a boy scout leader and have been working with a Merc 200 20 hp outboard that belong to my troop (approx 1974 model year, s/n 3760831). This motor was recently donated and we are trying to get it to work. We have two problems: 1, it is very hard to start. Once started it seems to miss a bit and will die when you throttle up unless you ease it slowly. Once the engine it hot it is very diffucult to restart. I have replaced the plugs, removed the carb and cleaned thoroughly. I am using new gas. Once you get it to high rpms it seems to run pretty good.<br /><br />Second problem: At high rpm and in gear the motor takes off with a good bit of power but then over-revs. I suspected the prop hub spinning out and had the prop rebuilt. It still does it. I am wondering if the prop is still the problem and just need to replace it with new, or could it be something internal. I changed the oil in the lower unit and it was clean (no milk) and no metal bits. I hear no unsual noises in the gearing (grinding etc.)<br /><br />Any thought????<br /><br />Thanks, Kenny Logsdon

 

[pittspilot]

Re: Mercury 200 20 hp outboard hard to start and slips

Did you fix this problem? I am having almost exactly the same thing

 

[kev_alaska]

Re: Mercury 200 20 hp outboard hard to start and slips

It still sounds like a carb issue. Someone around your neck of the woods should be willing to supply the troop with a manual for that model. Tell them it's their civic duty for the month. <br /><br />A carb rebuild should not run the troop too much money. As for the over-revving, is it possible that the motor is not trimmed down into the water enough? After the motor pushed the bow of the boat up, it will have a tendency to settle back into the water causing the prop to cavitate. If the motor is not trimmed down enough, it will overrev (not low enough in the water now) and not push the boat.

 

[mercpro]

Re: Mercury 200 20 hp outboard hard to start and slips

Kenny:<br /> Problem 1- If you are certain the carb is clean, open the idle screw 1/4 to 1/2 turn. For hard starting make sure the choke butterfly is closing completely.<br /> Problem 2- Cavitation is either caused by surface air or exhaust gases getting into blades of prop. If hub is new then check for damage to blades and then mounting height of the engine on the boat.<br /> Good luck and keep your stick on the ice.

 

[50horce_force]

Re: Mercury 200 20 hp outboard hard to start and slips

Hey man mine does slip also. I dont think it will be cavitation unless it happens all at once. we were out bout half an hour before it started sliping. My thoughs were stripped out prop. Had one fixed (still stripped) bought a new one still stripped. I took apart the lower unit and everything looks good no shaved metal or milky gear lube. it catchs in gear and idles fine<br /><br />one question though <br /><br />If the linkage was loose down in the lower unit<br /> would this cause it to slip when you try to run up the throttle.<br /><br /> twilson16@hotmail.com