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Old 10-23-2010, 03:06 PM   #2
Scraping Paint
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RE: Dumb Tender outboard motor question (winterizing)

If you're not going to be using your outboard during the winter, here's what's been recommended to us by the local Yamaha dealer with regards to extended storage.

The ideal storage position is vertical as you are proposing to do. Run the outboard (with the proper fresh water feed) and spray fogging oil into the carburetor(s) while it's running. The instructions on the fogging oil will tell you how much to spray in there, but I just put a lot in. The motor will smoke a lot and try to quit when you hit it with the oil so regulate the amount you spray in to keep the motor running. As soon as you start doing this disconnect the fuel hose from the motor (or turn off the fuel if the motor has an integral tank). Let the motor run as you squirt in fogging oil until it starves itself of fuel and quits.

Then remove the spark plug(s) and squirt a bunch of fogging oil into the cylinder(s). Turn the engine over by hand hand to make sure there is fogging oil on the entire cylinder wall of each cylinder.

Put the plug(s) back in and that's it. Running the motor dry helps ensure there is no fuel in the carburetor to get gummy over the winter and clog up the jets and other carburetor components.

At the end of the winter get rid of the gas in your outboard tank and start with new gas (add something like Stabil to make it stay "fresh" longer).

The new thing we learned from the Yamaha dealer (we replaced our old Evinrude trolling motor with a new Yamaha motor this year, hence the information) is to always run the motor (large or small) dry if you anticipate not using it for awhile. Like for a few weeks or a month or more. Today's gasoline goes bad pretty fast for a variety of reasons. Adding Stabil helps and Yamaha promotes a product called "Ring Free" which is supposed to help reduce residue buildup in the cylinders and on the rings (this may be nothing more than "mouse milk," I don't know). But running an outboard dry will help prevent fuel trapped in the fuel system from separating and gumming things up if the motor's going to be sitting for awhile.

We've been following this advice since and it seems to work.
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