I have a riding mower w/ 11hp b/s engine, which I just got out of storage (3 yrs). I put fuel in the tank then several minutes later I noticed fuel dripping from around the carb. I removed the air filter and observed a large quantity of fuel in the intake area. I disconnected the fuel tank and let the fuel leak subside. I then reconnected the tank and quickly started the engine, it ran fine with no leaks. However, when I shut it down the leak returned. I can't pinpoint the leak area. Please help...