Runaway Yanmar

kito

.
Sep 13, 2012
2,011
1979 Hunter Cherubini 30 Clemmons
It is a decompression lever and my only means of shutting it down.....other than covering the air intake. I can hand crank it easily with the lever up but not when there is compression. ;)
 
Jul 5, 2011
757
Oday 28 Madison, CT
Interesting. The lever in my cockpit (T handle on panel) is a fuel stop. This is Universal M12, not a YSM12 however. Very surprising your lever is decompression...... Does it say it is in the owners manual or on a parts schematic?
 
Sep 15, 2009
6,244
S2 9.2a Fairhope Al
Interesting. The lever in my cockpit (T handle on panel) is a fuel stop. This is Universal M12, not a YSM12 however. Very surprising your lever is decompression...... Does it say it is in the owners manual or on a parts schematic?
yanmar puts decompression levers (they keep the exhaust valve open when engaged) on there engines along with a fuel shut off lever for the injector pump universal dose not as far as i know
 
Jul 5, 2011
757
Oday 28 Madison, CT
Just looked at the service manual. Page 10-2 shows the set up and you are right. Stop control (standard version) was decompression. Optional was fuel shutoff control. From that I gather you could probably change it over, but it things ain't broke...............
 

kito

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Sep 13, 2012
2,011
1979 Hunter Cherubini 30 Clemmons
My manual says it has a decompression lever and a fuel stop. My Hunter 30 does not have a fuel stop pull knob, just a decompression lever. Probably because the ysm12 is a small single cylinder and designed to be manually started if needed. It's hard to get turning manually with the lever down but turns freely with the valves open.
 

kito

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Sep 13, 2012
2,011
1979 Hunter Cherubini 30 Clemmons
The ysm-8 that the OP has is basically the same as my ysm-12. Apparently O'day ran a fuel shutoff to the cockpit instead of a decompression. I would find out where the decompression lever is on the engine so you can use it next time it "runs away". Actually, I would rather have a fuel shut off in the cockpit. Only time I would need to use the decompression lever is to manually crank start it anyway.
 

Apex

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Jun 19, 2013
1,222
C&C 30 Elk Rapids
yes, YSM-8 is almost identical to the 12, with only some minor exterior dimension changes, which made it quite a chore to properly identify sans finding the mfr plate.

I will check this w/e when on the boat as to fuel shut-off or decompression. i am 90% sure it is fuel shutoff, esp in light of the FANTASTIC information all of you have shared so far.

Hand-Cranking - Before finding the poor ground, I had plenty of opportunity to hand start, and still do just for practice at times. The bruises on the back of my hand are a reminder to make sure the handle stays engaged while cranking away. :O) But I do know the location of the decompress lever, and will file that tidbit if information as another means to try and stop that train from grenading the engine should I have a similar episode.

Now, how to keep Bear from mucking with the throttle.
 

MitchM

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Jan 20, 2005
1,031
Nauticat 321 pilothouse 32 Erie PA
per Yan mar dealer Mack Boring the safest thing you can do to a diesel runaway is flatten the boat off a heel immediately. the engine is burning excess lubricating oil along wth diesel fuel. it's a particular problem with splash-lube engines on a high heel angle. on a one cylinder using the de compression lever should be 2nd choice. trying to block the air intake is not a good idea. starving the engine of air to halt combustion is theoretically possible if you have a heavy metal plate handy to slap on to the air intake, that's a lot larger than the air intake. a sponge or rag won't do it, those will just get sucked in to the air intake. then you'll have big problems trying to clean them out.