Meruiser 3.0L Alpha running rich

[izaver]

Hi ALL,
My 1998 Stingray with 3.0L Mercruiser I/O seems to be running rich. While the engine is running great, I noticed tons of black carbon in the air filter and on the sides of the engine.
I purchased the boat in late fall of 2008 and it had problems stalling before it warms up. One day I was replacing the spark plugs and noticed that the manufacturer's recommended MR43LTS that I bought were longer than whatever was installed in the boat. After I replaced the plugs, the stalling problem went away and the boat runs like a champ. So, I assume the carb was tuned up for the short plugs. And now it's running rich (correct me if I am wrong).
So, where would I start tuning it up? Timing? Carburator? What screws to adjust?
Please, advise with more details or the sequence (I haven't done this type of work, so I am still a newb here).
Appreciate your responses.
--iz

 

[JustJason]

Re: Meruiser 3.0L Alpha running rich

Id start first by making sure your flame arrestor is sparkly clean and that the choke is working properly.

 

[Don S]

Re: Meruiser 3.0L Alpha running rich

Also check the belt. If the pulleys are rusty and the belt is loose, you can bet the flame arrestor is full of belt dust.
Clean it, clean and paint the pulleys and replace the belt.

 

[fishinpa]

Re: Meruiser 3.0L Alpha running rich

First thing you need to do is get you the correct manuals for your engine and drive!
Read them over and over ,you will be much more familiar with what you are working with and will be able to use the info always ..

free manuals can be downloaded here if you look up in the ADULTS ONLY section .

fish

 

[izaver]

Re: Meruiser 3.0L Alpha running rich

Belts were loose. I just tightened them up after reading your replies. Pulleys seem to be OK. Maybe a little bit of rust. What paint should I use to paint them? Would high temp. black paint (mostly used for grills) be OK?
How do I tell the difference between belt dust and carbon? Or is it simply impossible to have carbon all over the place? (actually, it's mostly where the belts are!!!).
Thank you for all your replies.

 

[JustJason]

Re: Meruiser 3.0L Alpha running rich

uhmmm... you really shouldn't have carbon on the outside of the engine. That would be indicitive of a head gasket or manifold (exhaust side) leak.

If you wipe the black stuff with your fingers and roll your finger tips together and you get little rubber greasy rolls of crap... that's rubber. If you get more of a sooty ash, then thats carbon.

 

[izaver]

Re: Meruiser 3.0L Alpha running rich

If you wipe the black stuff with your fingers and roll your finger tips together and you get little rubber greasy rolls of crap... that's rubber. If you get more of a sooty ash, then thats carbon.

I get " little rubber greasy rolls of crap",they form a ball, definitely not the ash. I did replace the alternator belt last season and that's when it started, I guess. Now, it makes sense.
Thanks again.
--iz

 

[JustJason]

Re: Meruiser 3.0L Alpha running rich

As far as your paint, sand the pulleys, then primer then rustoleum non-gloss/flat enamal is fine.