Small Engines (Lawn Mowers, etc.): small engine problem, murray riding lawnmower, hp engine

Question
i have a murray riding lawnmower with a 14.5 hp engine, the engine model number is 287707, engine type is 1272-e1. i have to start the engine with starting fluid then it will run normal for about 30 minutes, then it starts to backfire and quits running.  i can then use starting fluid and it will run for another 30 minutes and quit again.  i have fresh gas in it.  i would very much appreciate your opinion.

thank you.

Answer
sonny
You have carburetor that needs cleaned or rebuilt.This carb is starving for fuel You may have a obstruction inside the carburetor and the only way is to take it apart and clean it out with a good carburetor cleaner. Find out which carburetor you have. There are 2 Carburetors that Briggs used for this engine 1 is a Nikki the other carburetor Walbro. If you get back with me I will if we have them in stock.