Another outboard mechanic needed!

[Stein]

Jesh, just when I got the 4 hp going, the 40 hp Merc decides to not play nice.

Like the other motor, I have owned this one for a little over a month.  No hour meter, but I have ran over 25 gallons through it which is a bunch of use in a 40 hp.  Up until yesterday it has run flawlessly.

I did manage to ultra flood it in the driveway when I was testing out the new tachometer.  I pulled the plugs and they were fouled.  I semi-cleaned them and it ran ok for about 10 seconds and then back to not idling.  I bought brand new plugs and it sorta ran ok and now it won't idle again.  Over 1500 rpm it runs ok to great, but I can't get it to stay still at 1,000 much less the 700-800 it should be at.

Here is a video of it running and a still of the plug immediately after this run.  The run was with the engine warmed up.  There is a bit of oil on the plug, not sure if this is normal or not.

One more picture shows the side of the carb and a threaded hole with nothing in it - should there be a bolt in there?  Seems strange to me, but I know next to nothing about 2 stroke engines.

I run only fresh ethanol free fuel with Stabil.  Last week, I ran a tank treated with Seafoam.  I'm a bit confused here, wondering how it could run great one day and then like this the next.

Thanks in advance.

http://youtu.be/88Mbe5MkgLQ

[FC]

Looks like you lost a low-speed metering screw (guessing from the pic and description of running condition).

[Stein]

I ordered a shop manual and also found other pictures and there is no screw in that empty hole.  My mixture screw was out about 2 1/4 turns and it sounds like factory is either 1 1/4 or 1 1/2, so I might try screwing it in a turn and see if that helps.

Anyone know if the screw is metering air or fuel?  If it is running rich, I'm not sure if in more or out more would be the likely way to go.

I'm also going to replace the fuel line and bulb as it sounds like aftermarket are prone to fail.  I do have trouble sometimes getting the bulb to prime and firm up.

[FC]

Turn the screw out to richen. Start by turning it in slowly until the motor bogs, you should be able to easily stall the engine like this. Turn the screw out until highest idle is achieved, when highest idle is achieved, turn it back in just a touch and set your idle to proper rpm. Make all adjustments with engine warmed up.

[lokidog]

You've got a Mercury... problem discovered.      

Seriously, I don't know a single Mercury owner out here that is happy with their engine, including a 9.9 owned by me.

[Stein]

I have a 15 hp bought new in 2002 that has never given me a single minute of trouble.  It runs like a sewing machine and starts on the first pull.

In my research, the internet is full of don't buy XYZ and then the next page is XYZ is the greatest.  I have owned and operated Mercury, Yamaha and Honda and I really don't have a preference.

I did find some ethanol deposit chunks in the fuel filter and am probably going to replace the fuel lines as well.  Although these motors are supposed to handle ethanol, they sure don't seem to like it much.