1983 Merc 25 hp problems

[WhiteMoose]

Wondering if you guys could help me on where to start with this problem.
I have a 1983(?) 25 hp mercury that hadn't run in oh 20 years or so, until I dug it out of a basement and fired it up last year. All I did to it before I got it running was replace the impeller, spark plugs, and lower unit oil.
It hasn't ever ran great for me. I always have to leave the choke about 1/4 on to keep it runing, and it always took several pulls to start, but the last couple times out, it wouldn't stay running at all. It would start after 6-10 pulls, idle ok, then the moment I gave it any throttle, it would sputter and die.
My first thought is I just need to clean the carb, since its prob. never been done. Does anyone have a good set of online step-by-step instructions on how to do this? Anything else I need to do or look for?
Thanks!

 

[FuzzyGrub]

I agree that the carb is probably the right place to start. May also be fuel pump (diaphram rot) or other part of fuel system. I have the merc sm for the 25hp, but its for late 90's motors. Look in the stickys above, there might be a link to one for your vintage, or another site to search.

 

[crazymanme2]

The carb on that motor is pretty straight forward.I agree on above (carb & fuel pump) also make sure your primer ball is working.

That's a great motor,don't give up.