Black smoke and rough running when starting

yensid

Petty Officer 3rd Class
Joined
Aug 6, 2001
Messages
85
Hello, all! My problem is with a Mercruiser I/O (can't remember the exact year, mid-90's - doing this from work without all the details). The boat is with my parents, and they just got it in the water a couple of weeks ago - it's been sitting since last winter. They said whenever they start it, it runs extremely roughly and has black smoke coming out until it is warmed up. Correct me if I'm wrong, but this sounds like it is running too rich while choked, right? If so, should I just adjust the choke to resolve this? It had been working better last summer - it was always a little rough right after starting while the choke was on, but not nearly to that extent.

OK, some background. This is actually my boat, but we've been sorely separated for over a year. Last summer when visiting my parents a couple of states away, I notice damage on my trailer when we were about to head home. I didn't have time to get it fixed, so we left it there. It's been there ever since - I had it winterized and stored it there over the winter.

At the time, it had been having some alternator problems. They just finally took it in to a mechanic, who swapped out the alternator and the starter (apparently it was having starting problems, too), and flushed the oil and changed filters, etc. Nothing else was done with it.

Thanks in advance for any advice!
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Re: Black smoke and rough running when starting

You didn't provide much info. We really need engine year/type/serial number etc.

Just based on what you said. Yes it sounds like an either stuck choke or severely mis-adjusted choke.

Try adjusting the choke to wide open and disconnecting it. Gas engines in the summer usually don't need much choking.... Since recreational boats are usually used in warm weather the choke requirements are usually minimal.

Out here on the Left Coast I have always adjusted my choke to wide open and disconnected it. Your requirements/results may vary.



My next boat engine will be fuel injected.



Cheers,


Rick
 

yensid

Petty Officer 3rd Class
Joined
Aug 6, 2001
Messages
85
Re: Black smoke and rough running when starting

Yeah, sorry, I hate being so bad with the info. For some reason my mind is blanking on the year. 1987? It's a 4.3l Mercruiser Alpha One, I believe, on a 17' Sea Ray. I'll be with it next week, with all my paperwork and manuals, and will be looking more closely at it then.

I'm not sure why the choke would become misaligned - stuck seems more likely? I'm thinking forcing it open should be good. I don't run it in cold weather much.
 
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