Really simple problem; where's the mixture adjustment?

I have a late 90s' long shaft 2 point something hp that I use on my sailboat. The boat partner who has the manual is long gone. Markings on the housing are worn & useless so I can't provide much more than that. But the problem is simple: the engine will only run with the choke full on.
Today it went through a full tank of gas for what should have taken a thimble full.
I found the idle adj. screw but cannot locate the mixture adjustment. Is there someplace I can find a diagram of the motor? Without spending a fortune on a new owner's manual?
Sidebar: how can they get away with charging an outrageous sum for something that they PDF provide via PDF for I'm? Clearly I'm out of touch.

Thanks for your help.

Re: Really simple problem; where's the mixture adjustment?

Welcome to iboats!!
Do you have the serial #? It's needed for the experts here to help (which I am not one).

Re: Really simple problem; where's the mixture adjustment?

eepks said:

Welcome to iboats!!
Do you have the serial #? It's needed for the experts here to help (which I am not one).

Click to expand...

Thanks. It's nice to know there is a place like this.

Re serial #:
Between my bifocals and the fact that I'm hanging half out of the boat while trying to adjust things (only way to reach a running motor on the back of a sailboat), it's hard to see anything. I can get the serial # but I won't be back to the boat for a week. I had hoped to educate myself a little in the meantime.
Am I correct that there really is no source for engine diagrams, short of paying full-bore for an owner's manual?

Re: Really simple problem; where's the mixture adjustment?

A number of the small Mercs (don't know about yours) only have idle mix adjustments, fixed jet for high speed. You can find online parts breakdowns (link below), but you'll still need your serial number to know which one is correct for your motor.

http://www.mercruiserparts.com/selectModels2.asp?type_id=MERC

Re: Really simple problem; where's the mixture adjustment?

Thanks for the link...
Ohmigod:% Ohmigod! I had no idea there were so many variations. Now I get why you need the serial number. I could thru thru these diagrams for days and still not be sure I got the right one.
Let's go back to simple...
... so it appears it only has one adjustment screw. and I've fiddled with it all over the place. I can't seem to get the engine to Howcome normally. Howcome I have to have the choke full on for it to run at all?
Could it be as simple $) as a dirty plug? I hate to waste your time....:/:/

Re: Really simple problem; where's the mixture adjustment?

On mine it's seat the screw lightly, then 1 1/14 out.