On Mon, 06 Dec 2004 21:14:42 -0500, Wayne.B
wrote:

I have a Yamaha 15 hp that is ten to fifteen years old. It was on the
inflatable dinghy of the trawler I recently acquired. The engine will
start in neutral using about half choke and it will rev up quite
nicely. When you throttle back however it will stall immediately
unless you can catch it with the choke and jockey back and forth.

By carefully playing choke vs throttle you can get it slow enough to
put in gear and it seems to develop decent power at higher revs
without any choke. It still won't idle back to lower speeds however.

Any ideas?

Low speed jets - either adjustment or dirty.

Get some Gumout Carb Cleaner, run the engine for a couple of minutes
to warm it up, the spray the hell out of the carbs at a mid-range
throttle setting (that's just to keep the engine running - no other
reason).

Do that a couple of times and see what happens.

Other than that, you need to adjust the low speed jets - pretty easy
to do.

In My Most Humble And Strictly Amateur Opinion that is.

Later,

Tom