Quote Originally Posted by Donald Stonecipher View Post
Speaking from experience as a sears lawn mower technician, sounds just like the vent in the fuel tank is plugged as mentioned before me.
Just like mower starts and idles fine, drive around yard for about 20 minutes and the sputtering starts and dies. Usually its just dust from mowing that is plugging a very fine hole in the gas tank cap.
Hope its just as simple as this for your sake.
I took the vent line off and checked it , it is not stopped up and didnt seem like it had been sucking together anywhere in the line . I took the line from the inside of the tank out also and it wasnt stopped up either.