I will try and make this as quick, short and simple as i can, lol. I have a 2008 Mercury 50 ELPTO two stroke carb motor that I bought with boat brand new 10 years ago. Never had a problem with it until my wife and I had twins so the boat set up for about two years with little to no use. Now I have time to get out and get back to fishing and took the boat out.

-Boat started and idled well with no problem with fresh gas in tank.
-When I applied throttle and got to 2k rpms the motor would start to stutter and sound like it was falling on its face.
-Sounded just like a carbuerated motor should that is struggling to get enough fuel
-while in this stuttering mode at around 2k rpms the tach would bounce from 2k to around 3k but motor didn't sound to be revving near 3k.

-completely cleaned out gas tank again
-replaced plugs
-replaced primer bulb and gas line from tank to outboard
-replaced fuel filter
-pulled the 3 carbs off cleaned them up really good (mild amount of varnished gas but didn't find any real clogs or issues that I thought could have restricted fuel)
-replaced rubber fuel lines that feed fuel filter and lines running to carbs.
-got a kit to replace all the insides of the fuel pump and did so.

Put new gas in her and she started up with no problem, sitting in back yard with lower unit down in a 55 gallon plastic barrel full of water. Idle was higher than normal, bouncing between 1200 rpms and 1800 rpms with a little rough hesitation every 10 seconds or so in neutral.

I did not check the reeds before putting the carbs and everything back together but i have read that the symptoms of a damaged reed will cause fuel to blow backward toward the air box out of the carb. With the airbox off and putting my hand over the carb i cant feel any fuel spray coming back out of any of the three carbs.

I did notice that the bottom carb had a small amount of gas mixed with two stroke oil lying in the bottom of the carb tunnel but not a lot. (is that my sign of it being a damaged reed?)

So with that being said, am i missing anything? Do i just need to adjust the idle on carbs (i didn't touch the adjustment screws during carb cleaning) or does this sound like a damaged reed?

I guess i should also say that when the boat was put up before the two year time period of no use it was running great.

Your help is appreciated!

I am thinking carbs need a better cleaning. If you did a top notch cleaning job then I would suggest adjustments. Can't do those in a barrel. You need the motor to be under a load for that. A service manual for the adjustment prodecure will help alot

Don’t worry about your reeds, they are fine. Sounds electrical from what you describe. I would be looking at the stator or switch box.

Try this, tilt engine up. Remove spark plugs and fill cylinders with sea foam (wal mart). Pour some sea foam into carbs. Put a full can of sea foam to every six gallons of fuel (in your gas tank). Let sit overnight. Next day start and run until engine cleans itself out! You won't believe how much smoke will come out exhaust. Bet it will make her hum!! Been doing this on racing outboards for many many years.

you need to do a better job on cleaning the carbs, were the high speed jets removed and cleaned ? were all the ffuel passages cheched and cleaned ? carbs are the most common problem with an engine that wont run correctly after the engine has been sitting for a long period og time. reeds and ignition will not usually fail from just sitting. you will be better served by totally eliminating the fuel system as the problem first

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This is what I would do first^^^^

I have the same engine on my boat, and it occasionally does something very similar--usually at the end of the day somewhere between 11 and 17mph.

I have noticed that when the battery is charged really well and at the beginning of the day, it rarely happens (check the battery health also) Agree with the prior electrical comment also as a possibility, and maybe the fuel pump?

Im thinking this is probably my problem i have some experience cleaning carbs on small engines and usually do not have to remove jets to get things clean and running right but im going to go through it again. I also didn't remove the idle adjustment screws and i read just a few minutes ago online that I need to do that as well and mark their original spot before removing. I basically just took the carbs off made sure the floats were working correctly and sprayed cleaner through every hole in the carb and made sure flow through those areas was abundant.

I was going to make a one gallon to one can of seafoam ratio and run it through the motor to clean everything but i hadn't heard about pouring seafoam in the plug holes and drenching carbs to soak. I guess this is safe to do since two people have recommended this technique. I just worried about that process since this is a two stroke motor. Im not a mechanic but in my mind i first thought this would wash the cylinder walls from any oil residue that would aid in lubrication once initial start up is commenced.

I also thought my original issue when working on it the first time was due to plastic crumbles that i found in the fuel pump when i took it apart to put in new internals. The plastic pieces were from the little pegs that lock in the little plastic circular diaphrams were setting in the bottom of the fuel pump casing.

I guess its back to getting the carbs fully cleaned but im gonna try the seafoam trick as well.

I would deliver to an authorized Mercury mechanic and let him go through the carburetors. Carbs have many orifices that can become plugged with varnish and deposits.

If your going to run that much sea foam.. i'd certainly run a little extra oil in that fuel to protect the cylinders

I will if I cant manage it myself, but i usually work on my own vehicles, lawnmowers, house repairs etc. Im fairly mechanically inclined and love to learn DIY stuff as well. I already have an outboard mechanic that many friends of mine have used for years that they trust if i cant figure this one out.

I wouldn’t lean on the Sea Foam too much. I know some folks believe it will cure cancer, but to me it’s just a maintenance tool that does have a specific purpose. Have you tried priming the motor while it is bogging? If it is a carburetor issue the motor will respond to the priming. If it does not respond to the priming, look to your ignition. I look forward to the resolution, so please post the fix.

^^^^^^ What he said,....get it done right.

Cleaning a carb is just that, an experienced mechanic will do a very good job at it which most amatuers don't. It just takes time and being thorough. You need compressed air, carb cleaner in a gallon can, carb cleaner in a spray can, some small wire like giatuar string to poke in holes. Take the carb apart completely. Remove rubber and plastic pieces and set aside. Then dip the carb and all metal parts. Let it soak for 15min and blow it out with compress air. Then poke all the holes you can get wire into. Then blow carb cleaner through holes. Reassemble. Simple, not rocket science. Link n sync and adjusting takes more experience and technical knowledge.

If it were me I would leave the idle screw alone. It is easy to clean out on the motor if it needs to be. But first clean the carbs well then test. Setting idle is a whole new can of worms. If you want to, then mark where it sits, screw inwards counting the rotations until it seats itself and mark the seat position. This way when you decided to reinstall it you have an exact starting and end point.

So by "priming" i am assuming you mean squeezing the bulb? I was told when i first started that when its struggling to run, to pump the bulb and if it causes the outboard to respond well and start to take off, that would mean that the fuel pump wasn't doing its job at getting enough fuel to the carbs but that the carbs were good. Early on I went to try this on the lake and the bulb was tight so it made no difference in how the boat ran. I have since then replaced the bulb just because I was replacing a lot of the other fuel system components already. I haven't been back to putting the boat in the lake since this high idle issue has started after cleaning the carbs.

It only trouble shoots an air leak in the fuel system or a bad fuel pump won't do anything if it is the carb. You can use your fimgers to partially choke the carbs by holding them over the carbs intake. If this cause the motor to level out and run smooth, it means you have a carb issue and/or adjustment issue or both.