Idling Issues

[radiohead]

Fired up the boat today for the first time since bringing it out of winter storage. Started up just fine like it does every year. However I noticed while idling, its normal idle is about 1700 RPM. About every 15 seconds it would kick down to 1000 RPM just for a second or two and and then kick back up to 1700.

Never noticed it before. Is this normal for an outboard motor that has been sitting in storage all winter or might there be an issue like bad plugs or something?
The motor in question is a 115hp 2-stroke Mercury. The plugs are about 3 years old.

[Laketrotter]

My first thought is old gas or water in the gas. I would try a fresh tank running it from a 5 gallon remote tank. A new set of spark plugs wouldn't hurt , three years on the same plugs, I think you got your money out of them.

[sirslurpee]

i'd at least pull the plugs and see what they look like.. make sure it's not running rich/lean anything..

[ENCORE]

I change plugs every year. Minor maintainance cost. Head to one of the auto stores or a marina and pick up some SeaFoam. Mix it according to the directions. Heavy won't hurt. It will help with two things, any moisture and varnish.

[TONGA]

Yea I think it needs to run, and like Encore said run a tank with some seafoam in it, it also dose a fine job of cleaning the carbon out of a motor just don’t be alarmed if you see some nasty stuff in your exhaust

[radiohead]

Thanks for the tips everyone.
I think I'm gonna take it into the shop tomorrow.
It's been in my garage for a couple weeks since I brought it home from storage. Yesterday I pulled it out into the driveway and hooked up the water muffs to the outboard and ran it about 5 minutes (this is when I noticed the RPM dialing down every 15 seconds or so).
Today my wife mentioned she thought the garage smelled like gas. I go out there and see a spot on the garage floor underneath the outboard about the size of a dinner plate, it's gas.
Doesn't seem to be wet to the touch now so I think it must have leaked out right after I put it back in the garage yesterday, but I don't think its normal for gas to leak out of the outboard.
Gonna play it safe and take it in.

[TONGA]

Yea I would say leaking gas is a different story

[love2fish93]

carb seal issues I would think if it is leaking. I see alot of this in school, someone will bring in a lawnmower and say its dead and we just throw a $11.95 carb rebuild kit on it and it runs like new. Just a thought. the seafoam was my only other idea.

Hope this helps,

Pat