Merc Running Rich? Black residue

[pikiewicz]

I have a1989 4.3 liter merc that seems to be running rich leaving a black residue on the stern. It has one adjustment low in the front of the carb. Can this or the choke be the problem? Kinda smells like a 2 stroker at idle.

 

[cooter2506]

Re: Merc Running Rich? Black residue

Sounds like your choke is too tight or maybe not opening at all. Remove your flame arrestor and see if it is opening after engine is running for a minute. Also adjust the choke cold so you can see about 1/8 inch of gap from choke to side of carb.

 

[pinecrestwoods]

Re: Merc Running Rich? Black residue

Have you done anything to it the carb recently? If you didn't adjust the idle mix. screw, then I don't see why it would get out of whack. Likely a choke issue, unless you were messing with that screw. Could be other things, but your choke would be a good place to start.