I have just aquired a 2hp mariner motor for my Jon boat and it was not running properly. So I cleaned out the carburetor and it started to work fine but after 2-3 minutes of running the motor it just died on me. I let it sit for a while and tried it again and it fired right up but died again after a few minutes. When I got it home I noticed oil was leaking out of the exhaust. What do I need to do to fix this?