200 hp Black Max Running Lean - help

Joined
Jun 19, 2007
Messages
4
Have a 1983 200 HP Black Max.

Was running fine at approximately 3500 for around one hour when all of a sudden it felt like it was skipping out of gear or not getting gas. We lowered the RPM to below 3000 and made it to dock. After that when we restarted the motor it would idle very rough and at a much lower RPM level. (Normally it idles at 1000 RPM but now it is only at 600) In addition the engine would almost stop working as we approached 1000 rpm but if pushed though that level it would run o.k between 1500 to 2800 rpm. As soon as we got close to 3000 rpm the engine would kick out again.

The fuel seperator is clean, and carbs have been redone, the fuel hoses replaced. This has not fixed the problem. One mechanic suggested that there could be some loose connections on the stator plate beneath the flywheel however he said that only a Mercury dealer could fix it.

We then took the boat to a mercury dealer. They also believed that it was a carb problem and once again redid the carbs and replaced fuel hoses. They also did a pressure check to confirm that the carbs were getting full of fuel. They also checked the compression which was fine.

They have indicated that the boat is running in a lean condition and apparently sucking air from somewhere else. He indicated that it could be a problem with the seals but did not recommending further investigation because of its age.

Is it time for a new motor? Any suggestions.:confused:
 

andy6374

Lieutenant Commander
Joined
Aug 4, 2005
Messages
1,617
Re: 200 hp Black Max Running Lean - help

The say it's running lean...ok

Do the plugs show signs of running lean? If it was running lean it wouldn't take long for it to show up in the compression numbers, which they said were fine. Have you tried pumping the primer bulb while running the engine, does this help?

Do you have spark on all 6? Did they check the stator with DVA?

I guess I am asking all these questions because I'm not totally sold on the running lean proposition.
 

j_martin

Admiral
Joined
Sep 22, 2006
Messages
7,474
Re: 200 hp Black Max Running Lean - help

It could be a simple as the gasket under the reed plate. A seal wouldn't affect the whole engine, just one cylinder.

Usually, if fuel is really screwed up, it's pretty easy to find it at Idle. If it is a restricted fuel flow, or even a small air leak in the fuel suction, it usually doesn't show up until you're going like a bat out of hell.

The first thing you need to replace is your mechanic.
 
Joined
Jun 19, 2007
Messages
4
Re: 200 hp Black Max Running Lean - help

Thanks,

When I choke it then idles better for a few seconds. I don't think they checked the stator and I have now moved the boat to a new mechanic after of $600 bill. I'm also not sold on the running lean idea.

Lorne


The say it's running lean...ok

Do the plugs show signs of running lean? If it was running lean it wouldn't take long for it to show up in the compression numbers, which they said were fine. Have you tried pumping the primer bulb while running the engine, does this help?

Do you have spark on all 6? Did they check the stator with DVA?

I guess I am asking all these questions because I'm not totally sold on the running lean proposition.
 
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