Black Smoke Yanmar 2GM20

[ATC]

Check to see if when you start the engine, do you get a slick/film on the water. If so the mixing elbow is restricting the exhaust causing unburnt fuel and a loss of power.

[Skippie]

I have a similar problem...a Yanmar 2GM20....which starts, runs up to 2,000 rpm and then idles up and down and when under load, goes down to zero/quits.

I have had fuel problems. I can't seem to get the fuel line out to take off the line filter in the tank (tank top has limited access to withdraw the top to get at the inlet strainer.

I have read where it might be a timing problem, might be injectors problem and might be restricted fuel line problems (inlet strainer). Fuel filters were cleaned/cleared.

Help...should I just call a mechanic and be done with it?

[Dkdoyle]

Interesting info. I have been having the black smoke symtoms for about a momth or so and just lost power at high end. Luckily my husband is a deisel mechanic and has started down the process. Prop being checked this week, Injector tested, going to look at elbow next. Mines only a one cylinder sio there is just not much too it. If you have ever had a potato plug your exhaust pipe in your car it it the same thing, back pressure. Will let you know.

[DeepFrz]

Skippie, when you do get that strainer off the pickup tube, walk it over to the nearest dumpster and say bye, bye. Or save it in a scrap book or something, but don't put it back in your tank.

[Howard Augenste]

I would check air filter first 9 out of 10 that is the problem

[Dkdoyle]

Well after much investigation and taking off the elbow (clean), the injector tested (works correctly), throttle cable, air filter, etc. I called my diver who does my boat every month and told him I was having a problem and I need him to check out the prop thinking I had a line rapped on it. He said it had a little growth. Humm. Well I took it out Saturday and Sunday and everything is back to normal. Thinking I need to fire this diver. Best of luck to anyone else with troubles.

[jconnor3]

I had the same issue and returned to port same day. Bottom guys were scraping the hell out of the shaft and prop as I was napping in the quarterberth. I called the guy that night and asked what that was all about. He said they forgot to do the bottom last month and were really challenged by the growth on prop and shaft primarily. Sure enough it runs like before with no smoke and no dropping rpm's. I added oil and she is back to normal. Simple things indeed.

[rrranch]

Id be willing to bet you have a air leak somewhere between the fuel pump and the tank. I run into this problem a lot in my line of work. On my new tractor it was the fuel water seperator housing had a tiny crack none could see. The dealer screwed with it three months under warranty and. My symptoms were identical to yours. I ended up finding the problem when I bypassed the filter. Check the fuel system again by bypassing everything from the tank to the fuel pump with a cheap Inline filter. I do hope the bottom job fixed it but these kind of air leaks come and go for no good reason. A diesel would have to lug really hard to smoke luke that.