# Yanmar 2gm black smoke



## johnskolfield (Nov 18, 2012)

I love this little engine! A Yanmar 2gm20 that was sitting for a few years, had a marine diesel mechanic service it, change belts and filters etc and it's run great for about 20 hours until..............my portable tank was on a slant and it sucked up air, engine stops. I've since barely got it running by bleeding the secondary filter, and bleeding the injectors. The current symptoms are very specific: Very hard start, idles fine, black smoke when revving under load, very low power, can barely move the beast!

I've little experience in such things but love the challenge of solving the problem. 

Any advise would be very much appreciated!

John


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## FarCry (Apr 21, 2007)

Did you check your fuel filters? What is a portable tank? Will it rev fine in neutral? Is there a chance your prop is fouled? Could you have sucked water from your fuel source? Can you play with the decompression levers and see if there is a problem on just one of your cylinders?


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## johnskolfield (Nov 18, 2012)

Fuel filters are new as of 20 hours ago and i've checked them, prop was a little rough but I dove over and clean it up nice, can you tell I'm in Florida?, The boat has a 5 gallon portable tank, I emptied it and put clean fuel in 20 engine hours ago so it should be good, Don't know about the decompressions levers but that sounds like great thing to check. I'll research where they are. 
Thanks for the suggestions! John


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## FarCry (Apr 21, 2007)

johnskolfield said:


> Fuel filters are new as of 20 hours ago and i've checked them, prop was a little rough but I dove over and clean it up nice, can you tell I'm in Florida?, The boat has a 5 gallon portable tank, I emptied it and put clean fuel in 20 engine hours ago so it should be good, Don't know about the decompressions levers but that sounds like great thing to check. I'll research where they are.
> Thanks for the suggestions! John


How did the fuel look that you poured out of your portable tank? Are you familiar with diesel bugs? If not, Google it. Just because you dumped new fuel in doesn't mean there isn't a whole bunch of crud inside your tank that easily could have broken free when your tank tipped over. The time (20 hours) is absolutely irrelevant. In rough conditions with bad fuel it's not unheard to have to change filters in less than an hour of run time. What type of primary fuel filter are you using? Did you check the secondary filter on the engine too?

Could you elaborate on what hard starting means? Have you tried to push up the throttle when cranking to see if it starts easier? Have you ever tried to manually pump the lift pump before cranking the engine?

And what about revving up the engine in neutral? Will it do it without black smoke or is smoke only when in gear?


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## johnskolfield (Nov 18, 2012)

This is very helpful information. I appreciate your time.

The boat sat for many years so when a mechanic helped the old man move it they just hooked up a small plastic marine tank as they were concerned with what might be in the built in tank. 

Since I got it I've emptied and cleaned this little tank so it should be good. I'll research diesel bugs. As I was in a cramped space working to bleed the injectors I may have pushed the decompression valves some by accident. I didn't even know where they were but since have found them on line and they're right above the injectors. 

The small fuel filter by the injector pump looks like new (was replaced 20 hours ago), not sure if one can tell by looking if it is good or not. Is the primary filter the one that is a glass container to drain water out of? If so I've checked it for water but haven't looked closely at the filter. It also is fairly new.

Starting it is really hard to get it to catch. It will cough and try and come close with me working the throttle but very, very stubborn. Once running it idles fine without black smoke and will even idle at higher RPM's but if pushing the throttle quickly it will hesitate unlike before this problem. 

It ran perfect and always started immediately weekly for the last three months. I may have goofed in how I bled the fuel but have double checked all the fitting s to make sure I tightened them up properly.

Thanks again,

John


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