Gray Smoke At The Start

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Joe Mullee

Been doing some work on the engine. It's a slow process when you're new at it. Anyway lately when I initially get to the boat after a week or so and start her up there is a large cloud of gray smoke that comes out the exhaust. It only happens right at the start and only at the initial start. Subsequent starts during my stay do not produce the smoke at all. This didn't happen the first two seasons I owned the boat. I have a Yanmar 3GMF. Any ideas on why this is happening? Thanks, Joe Mullee
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
How do you shut her up (no shut her down).

Joe: There is a shut down procedure that Yanmar has in their manuals (probably good for any engine). Once you are ready to shut her down, you should idle the engine for approx. 5 min. @ 1000rpm to cool the engine down. Then you should rev the engine to approx 2500-3000rpm (rated speed) to blow out residue in the cylinders. Then stop the engine by pulling the engine stop lever to the fuel. This is not to say that this will take care of your problem, but you may want to try it out and see if it helps.
 
J

Joe Mullee

Steve,

Go to 1000 RPM for one minute, then to 2500 RPM. Two questions: 1) How long at 2500? 2)When I pull the choke is the engine at 2500 or do I idle down right before I pull? Thanks, Joe
 
B

Bruce

I Agree

Steve is 100% correct. Run your engine up to 2500 - 3000 rpm for only a couple of seconds and while it is at high rpm pull the engine shut off.
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
5 minutes at 1000.

Joe: You run your engine at 1000 rpms for about 5 minutes. This is the cool down period for the engine. Then you run it up to the normal operating speed 2500-3000 rpms and pull the kill switch (fuel shutoff). By running your engine up to this speed the engine will burn all of the fuel in the cylinders and die!!!
 
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