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Discussion Starter #1
Hey everyone!

I've been trying to fix my motor problems with only using prior posts, but now I'm just stumped.

I had an overheat problem, so I took apart the whole cooling system, cleaned it all out and water cools perfectly.

Well after this the motor wouldn't start. So of course I go into troubleshoot mode. Fuel system cleaned out, both filters, etc. Turn out, the stop motor cable was pinched.

Now, I'm getting black smoke, soot, unburnt fuel (nuetral and in gear).
I took apart the intake manifold and breather, both seemed clear.
I took off the exhaust elbow again, clean.
I replaced all the feul injectors with brand new ones.
With the exhaust elbow off, I started the motor and there was still a ton of smoke.

What have I missed??

My concern is that the motor didnt smoke before I started repairing it, so I think I did something during repairs.

Thanks for any help!
 

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Wish I could help. Our Yanmar has always smoked black smoke at startup. Maybe yours is just catching up with the times.

See if the smoke goes away when the engine heats, see if you are burning oil - if all that checks just move on.
 

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Discussion Starter #4
Wish I could help. Our Yanmar has always smoked black smoke at startup. Maybe yours is just catching up with the times.

See if the smoke goes away when the engine heats, see if you are burning oil - if all that checks just move on.
I wish it was just on startup. I took her out yesterday, and she smoked, carbon, the whole time I ran her.

Before I took her out yesterday, I ran the motor for about 30 mins at 2500-3000 rpm and it would clear up (no smoke, clear water).

I suppose I can have someone dive to check the prop.
 

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Black smoke is fuel not getting burnt properly (bad fuel/air ratio), not necessarily too much fuel, it could equally be not enough air getting in, a blockage in the exhaust system, or there is now too much load on the engine for some reason.
Is that all you changed, poked, prodded etc?
 

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Discussion Starter #8
Black smoke is fuel not getting burnt properly (bad fuel/air ratio), not necessarily too much fuel, it could equally be not enough air getting in, a blockage in the exhaust system, or there is now too much load on the engine for some reason.
Is that all you changed, poked, prodded etc?
Yes, so far.

My air silencer is off (the clips broke). That's something that has changed.
Would too much air cause this?
 

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How about decompressor not fully disengaging? Do the injectors have the little heat insulating washers on the tips? Too many washers? Try a spray/pop test of injectors >Reinstall upside down and hanging. watch for even mist or dribble.
 

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Discussion Starter #11
How about decompressor not fully disengaging? Do the injectors have the little heat insulating washers on the tips? Too many washers? Try a spray/pop test of injectors >Reinstall upside down and hanging. watch for even mist or dribble.
All 3 injectors are brand new and this was happening before I replaced the injectors.
 

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Discussion Starter #14
Maybe a gasket(s) re-installed backwards?. Maybe the timing was disturbed? Any changes made to the injector pump? "New" injectors?, maybe the wrong ones?, or a bad "batch"?

An obstruction in the exhaust system downstream of the manifold?

Paul T
They were OEM yanmar injectors, plus the smoke was happening before I replaced them.

I'm thinking maybe when I was clearing the cooling system, something clogged exhaust somewhere. I'll try searching/clearing more.
 

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Went back & read your original post. It appears the smoke started right after you cleaned the cooling system. Curious to know how you cleaned it? If it smokes right at the open exhaust manifold it could be something internal, either too much fuel or not enough air. If the timing or injector pump wasn't worked on you may be missing a shop rag? :D

Paul T
 
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