Outdoor Power Equipment and Small Engines - Lawn motor wont start and leaks gas

Hi group,
My Sears gas lawn motor been sitting in my garage for 3 years, last week I took it out, changed the oil, spark plug, filled it up (fuel) and it wouldn't start, as a fact, It was leaking gas, until about 1/2 the fuel tank, this leak was coming from the point where the airfilter attaches, I took it (air filter) out and it kept leaking.
My guess is the carburator. maybe an O-ring somewhere.

Any suggestions?
Anyone has a schematic diagram of sears lawn motor?

I am going to assume this is a Tecumseh engine (sounds like it from the info in your post). The needle and seat are not sealing in the carburetor. I imagine the float is stuck in the down position, and a good carb cleaning may be all that it takes to get it going again.

My neighbor had the same problem with his 18hp lawn tractor. The problem was the float was sticking.

I had a similar experience. I picked up a MTD 5hp that was sitting in a garage for 10 years and only run once. I poured gas in the tank and gas began pouring out the carburetor. I rebuilt the carburetor, kit was around $10.00. The black rubber gas hose going to the carburetor from the fuel tank was dry rotted so I replaced that. After doing this the engine starts usually on the first pull. It does look like you may have a carburetor problem. I you have a gas line hose going to the carburetor look at it carefully where the clamp is. Some hose clamps can cut into the hose causing a leak. dave