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Old 03-06-2010, 10:52   #16
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yanmar question

wot test at the dock, max rpm was 3000. at this point the throttle lever was blocked by what looks like a factory drink holder on the pedestol just under the compass. someone please tell me this isn't my problem. the throttle lever was pointing 10 degrees off of straight up.

there is a little puff of black smoke when the motor first starts, after that nothing for exhaust smoke all the way to 3000.
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Old 03-06-2010, 11:18   #17
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Well, the blocked throttle is at least half of your problem. Fix it and try again.

The leak from the antisypon valve is typical. Pull it off and soak it in Rydlyme or CLR to clean it up. It has nothing to do with your exhaust elbow fouling.

Your inpection of the exhaust elbow is interesting. I guess if you had seen dozens of them in various stages of fouling it would be telling. A year ago I had a Yanmar mechanic do the same thing and pronounced it ok. I still would be suspicous however.

Puff of smoke on acceleration is perfectly normal. The fuel injector is pushing more fuel than can be burned cleanly to try to accelerate.

I do think that although you may have found most of your problem, fixing the throttle may not entirely solve it. Look at the prop since it is not oem.

David
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Old 03-06-2010, 13:07   #18
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disconnect your throttle cable from the engine and increase the rpm locally. or remove the cup holder or turn the throttle handle so you can push it to the stop on the engine.
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Old 05-06-2010, 07:34   #19
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Yanmar question

I disconnected the throttle cable and pushed the throttle lever to full with my thumb. Engine topped out at 3000 RPM again as a max. I have ordered a photo tach coming in on Monday and will test with this to see accuracy of RPM gauge. Talked to a mechanic to have him come look at the engine and he said I was crazy thinking the engine would do 3600-3800 RPMS. I told him what I am gettting for RPMS's and he said the engine is running fine. Starting to think I am chashing my own tail. Thanks, Mark.
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Old 05-06-2010, 08:35   #20
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The 3gm30f should do 3,800 in neutral at wot. That is what I have experienced and that is what the manual says.

Find another mechanic if he believes 3000 rpm is ok.

You could have two fairly simple problems at work here: a tachometer that reads very low but I doubt that low and a severely overpitched prop.

David
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Old 05-06-2010, 10:06   #21
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As others have said, per Yanmar, the 3GM30F is 3850 WOT, 3600 loaded for 1 hour, and 3400 continuous. If all things are correct, you should be able to get to 3600 in flat water. I have 2 of these engines, don't let the mechanic tell you otherwise. I cruise at 2700-2800 as this is the optimum torque/fuel consumption ratio.

FWIW, I tested my tachs with a photo tach. My Yanmar tachs are very accurate.
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