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morgan342 · 21-12-2015, 13:48

My yanmar 1 cylinder 12hp diesel died twice on me while under load. It starts up and I tested it on anchor. As soon as I get in the channel the engine slowly dies off. I just ran it and im getting black smoke with an odor and it died again. It wont start up right after it dies.
I am getting some white smoke out of my mixing elbow and I notice a little cut in my fuel line but it didn't go all the way thru.
What ive done:
1. Replaced fuel line that was damaged
2. Replaced both fuel filters
3. Tightened and rigged mixing elbow as good as I can get it.
4. Tightened all clamps
5. Checked fuel. No water, looks good
6. Checked oil, looks good.
Im in lake Sylvia, fort Lauderdale. I just need to motor to Biscayne bay where im stay for a bit to get some other boat work done. I rigged up my dinghy so if the engine dies I can jump in it immediately to tow it. If the engine doesn't work im not sure what to do next. I did everything I can think of. I just need to go 30miles.
All advice helps
Thank you

David Hughes · 21-12-2015, 14:02

White means unburnt diesel. That's likely bad injectors, bad injection timing, or low compression caused by a few likely culprits. None are good. And that is about the depth of my knowledge.

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shakey doug · 21-12-2015, 14:10

Being tired, have you refuelled and mistakenly used the outboard fuel??
Check stop lever return spring tension, lever may be slowly vibrating to OFF position.

morgan342 · 21-12-2015, 14:15

No I didnt use the outboard fuel and its not the stop lever.
Thanks tho

fishead · 21-12-2015, 14:20

Have you checked the exhaust mixing elbow ? If it is clogged it will start but won't make any power.

shakey doug · 21-12-2015, 14:22

Could the white smoke be steam by any chance?

morgan342 · 21-12-2015, 14:28

The elbow was loose but where it is I couldnt just turn it to get it tight so I rigged up a line as a temp until I get to my destination but obviously its not working.
I noticed the soot on and around the elbow. So I guess my next move is to try and get the elbow off and clean it out.
Do you know much about the elbow?

shakey doug · 21-12-2015, 14:36

They are known to choke up with carbon causing loss of power and rpm in a severe case particulaly single cyl engines to stop under load.

morgan342 · 21-12-2015, 16:07

Thanks for the help. I am going to bleed it and try in the morning. I dont want to crank up the engine and disturb the neighbors

Snore · 21-12-2015, 16:14

If you are repeatedly bleeding there is a vacuum leak in the fuel system. Bleed it and let it run for an hour at anchor. If it dies, it is a vacuum leak. Easy way to find a fuel leak is to bleed, start the engine, turn off the engine and place paper towels under the entire fuel system.

Wait a few hours and look to see what paper towels are wet, that is where the leak is.

tuna-tic · 21-12-2015, 21:16

I'm not very familiar with that engine but i do know diesels ok. You said you had black smoke so lets start with that before pulling anything apart.
Black smoke indicates that there is either to much fuel or not enough air.
* If there is an air cleaner check it and replace or wash if needed.

* If the air cleaner or foam filter is OK it could be a restriction that presents under a load. See if you stall or lose power with a NO load rpm test. not a bad idea to check the exhaust temp with a pyrometer if you have one.

*It could also be a bad injector. The injector needs to atomize the fuel to get your power, clean burn and efficiency. Especially in a single cylinder engine.

* an easy little thing I would recommend too would be to use Lucas or Diesel Clean fuel additives. (They sell it at walmart or any auto parts store) it makes a big difference lubricating and keeping you injectors clean. I barely get any exhaust soot on my transom anymore.

Good luck, hope its an easy fix.

irwin37 · 21-12-2015, 21:56

Is there a chance you picked up something on your prop shaft, black smoke also indicates an over load. Maybe a line that tightens as you get moving and stop the engine?