25hp mercury carb issue

[AugieDogie]

I have a '92 Mercury 25hp, serial OD226947.
I stored it last winter and used the Quiksilver storage fog in the engine.
Since I brought it out this year, I have not been able to get it running correctly. It will not idle and runs very rough a low speed. It will run full out extremely well.
To start it I have to play with the throttle a bit. It has a lot of grey gel (I believe is a mix of water and excess gas/oil) that comes out of the exhaust making me believe it is running rich at low end although that confuses me as I have to give it gas to get it started.
I have torn down the carb (6 times) and thoroughly cleaned it with carb cleaner ensuring that all of the jets and venturi are not plugged. I have installed a carb rebuilt kit and new plugs. It does run somewhat better after this work but still the same issues.
It has an idle adjustment on the choke knob which has to be turned up all the way to even come close to idling. I have also adjusted the idle screw, starting at 2 turns out and working it back. I find that when I turn the idle screw in all the way (full closed) it idles quite well?? I am afraid that this will be running too lean and fry the engine?
Any assistance would be greatly appreciated.

Augie

 

[AugieDogie]

Re: 25hp mercury carb issue

hmmm. I guess everyone is as stumped as I am.

I will try to adjust the linkage (although this was never moved before) and try to get the revs up that way so at least it will start and idle. If that doesn't work then I will have to take it in.

 

[AugieDogie]

Re: 25hp mercury carb issue

Took it fishing for a week. I adjusted the linkage which should have caused it to rev a bit higher so that it would idle.
Runs great a top speed, but then when I slow back down it won't idle until it sits for a few minutes.
It is using a LOT of gas. I went through twice what I normally do.
After pulling the carb so many times as well as a full rebuild, I am thinking that I should start looking elsewhere. I am good with 4 stroke repairs but I haven't quite figured out this 2 stroke stuff yet.

It looks like there is gas/oil sitting in around the engine which makes me think that the gasket where the engine mounts to the shaft is maybe leaking although I'm not sure why that would cause all of the issues I'm having (but I'm no expert).
The float looks fine, no gas in it, no cracks, and it seems to be sealing the needle.

I can't find an engine schematic anywhere.
Not sure whether I buy a repair manual (which may not help me solve my problems as I don't know quite where to start) or just take it in where I will probably be soaked for a pile of dough.

 

[15yroldmechanic]

Re: 25hp mercury carb issue

Your idle is not configured correctly.

 

[bigbadplad]

Re: 25hp mercury carb issue

I also own a 1992 25hp merc and have had many headaches with it. On the exhaust and water manifold they are separated by a gasket, you should remove and check both the water manifold to exhaust manifold and exhaust manifold to engine block gaskets, I experienced a leaking water manifold causing a greyish type mix to come out of the prop. Have you tried replacing your spark plugs? how about the float setting? is it set at the 1" height?(as measured when the carb is inverted and measured from the carb base to float bottom)