Thoughts on the Mercury Four-Stroke 9.9hp Outboard ?

[SayGudday]

Gudday!

(Hope this is the appropriate forum).

Have the opportunity to purchase a mercury 4 stroke 9.9 hp outboard for $1,500 with only 43 miles on it. Comes with lifting gear, jerry cans and a few other things. Does anyone have any experience with this motor they'd like to share?

Thanks in advance.

[bstreep]

We've had ours for about 2 years. Paid $1370 for it, brand new, from Academy. It was a floor model, but new.

This is a great engine. Seriously, starts nearly flawlessly (OK, sometimes I'm so confident that it will start that I take a leisurely tug on it and it doesn't start).

I guess the only thing I don't like is that over the years I've gotten used to shifting on the side of the engine, rather than on the shaft.

[chadlaroche]

I just purchased a 3.5hp I hope the 9.9 is better. On a 7 ft Livingston catamaran fiberglass dinghy(80lbs) it will barely plane with myself on board.add a second person and forget anything above 1/3rd throttle. but what really cooked my goose was 2 trips ashore (150) yds and the onboard tank was empty

[bstreep]

Originally Posted by chadlaroche

I just purchased a 3.5hp I hope the 9.9 is better. On a 7 ft Livingston catamaran fiberglass dinghy(80lbs) it will barely plane with myself on board.add a second person and forget anything above 1/3rd throttle. but what really cooked my goose was 2 trips ashore (150) yds and the onboard tank was empty

Being honest - our problem with our 9.9 is that the gas in the tank gets old. I swear it doesn't use fuel...

I wouldn't expect an 80 lb dinghy to plane with a 3.5...

[chadlaroche]

Originally Posted by bstreep

Being honest - our problem with our 9.9 is that the gas in the tank gets old. I swear it doesn't use fuel...

I wouldn't expect an 80 lb dinghy to plane with a 3.5...

fair enough I had a walker bay 8' with a 4hp 2 stroke that would scoot. I expected the cat to move as well. Everyone says they dont use fuel...time to upgrade to a 9.9

[ozskipper]

Originally Posted by chadlaroche

I just purchased a 3.5hp I hope the 9.9 is better. On a 7 ft Livingston catamaran fiberglass dinghy(80lbs) it will barely plane with myself on board.add a second person and forget anything above 1/3rd throttle. but what really cooked my goose was 2 trips ashore (150) yds and the onboard tank was empty

I dont think many people would expect a 3.5 to really plane. Particularly not on a catamaran style hull. maybe on a surfboard with an 8year old driver lol.

All that size motor is really designed for is to putt putt you to and from shore. I have a mariner 3.5 for my 8ft tender. We get around 30-40 mins motoring out of it depending on the loads.

Cheers
Oz

[SayGudday]

Thanks for all the feedback, I love this forum!

[cfarrar]

For what it's worth, I believe that all the small Mercuries (9.9 included) are now the same engines as the Tohatsus.

Colin

[David M]

How old is the engine? Have you tested it? How do you know how many hours "miles" it has?

I would definitely put it on a small boat and test it with a load. Seeing that it runs with mouse ears attached may not be good enough.

[SayGudday]

Thanks, David, I think I'm going to pass on this outboard for now, but thanks for the feedback. On a much more exciting note, it looks like I'll be taking ownership of my new boat on the 13th!

[ozskipper]

Originally Posted by cfarrar

For what it's worth, I believe that all the small Mercuries (9.9 included) are now the same engines as the Tohatsus.

Colin

Agreed. I compared a Tohatsu and Merc 5 yesterday and aside from the stickers and fuel switch they were identical.

Cheers
Oz

[Cormorant]

We had a Mercury 9.9 20" shaft for a few years, and it ran flawlessly.

Recently sold it and bought a new Nissan 9.8 (same as Mercury and Tohatsu) with a 25" shaft and an alternator. It also runs flawlessly. The 9.8 weighs about 25 lbs less than the 9.9, which I believe is really the 15HP motor with different carburetion. For our boat, that weight savings out on the transom was significant to the trim of the boat. And the deeper prop is wonderful when bashing into a head sea.

Both motors at less than half throttle will push our (5000 lb. -- relatively lightweight) 31' boat at 5 knots, and 15 statute miles per gallon. If we're in a hurry and want to do 6 or 7 knots, the mileage goes down to maybe 10 mpg.

Good machines all around -- treat them right and they'll treat you right. Sea Foam in the gas, regular oil changes, fresh water flush the cooling system whenever possible, fog the cylinders before winter layup, etc.

[SayGudday]

Awesome feedback, much thanks!

[Charlie]

I have a Mercury 6hp and it has ran flawlessly. The only time it didn't start was when I lent it to a friend and he didn't run the engine dry before storing it. When I came back to the boat a month later I couldn't get it to start. I flushed new fuel thru it and then it started no problem.

[David M]

Charlie,
Gasoline formulated for use in California is notorious for fouling carburetors. California gasoline cannot be left in carburetors for long periods.

With the boats at work that have carburetors, when done with the boat we require that the user of the boat shut off the fuel supply and run the engine until it burns all of the fuel out of the carburetors. The only outboards that do not have this problem are the ones with fuel injection.