1984 120 hp carb issue.

[utfisherman]

My 84 mercruiser 120 carb runs good but I'm getting black soot from the exhaust
It will idle on muffs but on the lake it's bogs and dies. I've rebuilt the carb new cap rotor and points to and plugs
I don't know why the black soot and how to fix it

 

[Scott06]

My 84 mercruiser 120 carb runs good but I'm getting black soot from the exhaust
It will idle on muffs but on the lake it's bogs and dies. I've rebuilt the carb new cap rotor and points to and plugs
I don't know why the black soot and how to fix it

Assuming choke fully open s, Most likely float level or too high fuel pressure both lead to higher bowl fuel level . Id start with float level and drop check or replace needle and seat Plus measure fuel pressure.

 

[utfisherman]

I'll try the float level. I didn't think of that thanks. I did put a new fuel pump on also.

 

[utfisherman]

A little follow up needed. When I check the float hight do I messure with spring in the needle compressed or messure it with the float just sitting on the spring?
I set it with it sitting on the spring no change.

 

[Scott06]

A little follow up needed. When I check the float hight do I messure with spring in the needle compressed or messure it with the float just sitting on the spring?
I set it with it sitting on the spring no change.

first one is a guy who rebuilds pontiac tripowers (same rochester 2 bbl design you have) so use your factory float specs

second one is from mikes carb parts he has lot of good videos on his channel but this one setting float height is not the best visually.

 

[utfisherman]

The video helped. I got it fixed thanks