Johnson SD-15 with Pressurized with Integral Tank?

[Buccaneer]

Some where I read something the other day about a Johnson SD-15
outboard with a "pressurized" integral tank.
I tried researching but found nothing but some YouTube videos
of said outboard running. While the styling was a little different,
I seen nothing mentioned about the tanks being pressurized.
Were the tanks pressurized? If not, is there different models
that are, and if so, "why"?
Thanks.

Prepare to be boarded!

[fisherman6]

Buc,
Yes, the SD-15 does indeed have an integral pressurized fuel tank. This was done because much of the fuel tank’s capacity sits below the level of the carburetor. Without a fuel pump or the pressure system, that capacity would have been unusable. With the subsequent model SD-20, the pressurized remote fuel tank began.
-Ben

OldJohnnyRude on YouTube

[david-bartlett]

+1 on what Ben said. Liquids do not like to flow uphill.

[garry-in-michigan]

The low speed carburetor Venturi ran off a small rotary valve in the center main bearing. They tapped into the back side to get the pressure. . . 😆

[Buccaneer]

Thanks for the replies. From you Youtube videos I could not see the
carburetor, nor where the bottom of the tank was. Make sense now.
Found a tank on EBay. They do indeed look "deeper" than normal,
and see how the tank bottom could be below the carb.
Funny about the "back side" pressure Garry!

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Prepare to be boarded!

[seakaye12]

Well….what do you know! I saw one of those at Tomahawk this past summer and was puzzling over what motor it was from. Different enough to stand out….and I don’t think the seller knew what it was either.

Thanks for the picture.

[jerry-ahrens]

I have an SD10 if I can find a picture… here you go..

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[jerry-ahrens]

You can make out the ”ventless fuel cap in this picture.

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[jerry-ahrens]

One more of the carburetor..

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[fisherman6]

That’s a sharp looking SD-10 Jerry!
-Ben

OldJohnnyRude on YouTube

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