I have a John Deere L118 Limited Edition (w/ 20 HP B&S engine), which I purchased about 8 years ago. It ran well with few problems up to late this summer. I believe the problem started when I accidentally filled the tank with some stale gasoline – the tractor turned over, but would not start. I drained the fuel tank and filled it with fresh gas, but it still would not start. When I use starter fluid, the tractor starts for 4-5 seconds, and then cuts off. I installed a new fuel filter. The connections in the fuel line seem tight, so while the problem might be the vacuum fuel pump itself, I do not think it is due to a leak in the line. I disconnected the fuel line at the carburetor -- fuel flows through the line at start up. But when I put the fuel line directly into the air intake (with some starting fluid), the engine still cuts off in about 4 seconds. I am not sure if the pump simply is not drawing enough fuel into the carburetor. I understand that, if it is a problem with a safety cut-off, the engine would not start at all (even for 4 seconds). My thought was that the problem may be a gummed up carburetor, but that would not explain why the tractor does not start when I feed fuel directly into the carburetor. Any thoughts about other things I can try before bringing the tractor to a mechanic?