Motor die's after running for short time?

While running my lawn tractor(model 917.289243 21hp Briggs and Straton 46 inch cut), after running for about an hour the engine stops. I've changed out fuel filter, changed the gas in tank, replaced air filter, replaced gas cap.

After engine stop there's no fuel in filter but full tank of gas { disconected the fuel filter going to the carb fuel run's with no problem's after hooking back up try to start nothing fuel filter empty? } there's two wires coming off the bottom of carb is this an electronic choke. At my wit's end, mowers only two years old warranty ran out three months ago started having problems one month ago go figure. Sears said they could send someone out for a $99.00 charge, to tell me what's wrong. I'm a disable vet with limited income so for now I'm hoping someone could help.

Chuck