Black Smoke/power loss in 9.9 Yanmar

[Scott Blahnik]

I have been having problems with the diesel on my 2001 270. It started with soot, the went to overheating, which was corrected by replacing the impellor.This weekend, at full rpm's the power suddenly decreased, accompanied by black smoke. Now I'm getting about 1/2 speed ( around 3 knots) max, and it's not overheating.I know, sounds really bad.I checked the archives and found some interesting advice-such as try automatic transmission oil in the gas tank, to checking out the "mixing elbow" on the exhaust.My question is: has anybody had a similar experience and how was it corrected?Right now my plan is to call the Yanmar people in.Thanks,ScottS/V disabled Hello Dolly

 

[Roy Mosteller]

Mixing Elbow

Sounds typical of a fouled mixing elbow to me.

 

[Mark M Smith]

Black Smoke

Means you are burning oil! Or too much fuel, or the motor is overloaded. Your motor is too new to have the exhaust elbow clogged Unless you run the motor at low rpms alot. The thing that bothers me is the loss of rpms. It can be injectors/fuel pump also! no quick answers here, sorry.

 

[Tom]

Black Smoke

Did you check your prop? If you've fouled it with someting this could cause loss of rpm and black smoke. Also a coked up mixing elbow could cause similar symptoms. If you've only run your engine to get in and out of the slip could be coked up with < 100 hrs. A piece could have broken loose and clogged up an already restricted passage in the elbow. It is probably something simple so start with the prop and work your way up.TomS/V Miss Jenna

 

[Scott Blahnik]

Thanks-

I've been reading a lot about the mixing elbow, and actually I'm somewhat hopeful this is the problem...the impellor was shattered, so I know all those pieces had to go somewhere, so maybe it won't cost a fortune. If it's the injectors, is this a major, expensive job, akin to replacing head gaskets, etc.? Also wondering if my warranty covers it...

 

[Andy]

Clogged Injectors

Like others, I think you boat is to new to have the clogged mixing elbow (an overblown culprit in most replies). Despite the ruggedness of a diesel, the injector nozzles of the engine are very sensitive parts. Running bad fuel (dirty or watery) through them can cause them to release too much fuel into the cylinders. Too much fuel, not enough burned=loss of power and black smoke. Run a high concentration of diesel cleaner through. If that doesn't help, I suggest you find a diesel mechanic that will trade and injector test/nozzle replacement job for an afternoon on the water (add one case of beer AFTER the job!)

 

[Steve Dion]

New Injector!

Scott:If Andy is correct, you are only looking at about $85 for an injector. You want to check out the other options too.I sort of doubt that the mixing elbow is your problem. I only say this because it tends to overheat when you have this problem.There are places that will sell you a rebuilt injector for about $20-35 (exchange price). I would pull the injector and see if there is anything that looks obvious (carbon, rust etc). Find a shop and see if they can test it for you.