I have a 12 hp briggs rider, that starts and runs fine for about 20 to 25 min. and then it sputers and wants tostop . New filter , new gas line, new plug , clean air filter,new oil, engine is clean . Can a small engine get vapor lock?
Thanks for any help,
Barry S

Hi,
It is right at the time area where it could be fuel or ignition. Does it recrank after cooling. That would most certainly be ignition. If you can get it to start again, check for spark after it stops.
Peace,
Clarke

I had the same problem with mine and it turned out to be the Air/Fuel mixture adjustment. One the engine gets hot it requires more air to run properly. There should be a screw on the bottom of the carburetor bowl with a spring between the bowl and the head of the screw. Try screwing it counterclockwise to "lean" out the mixture. This should fix your problem. The screw usually can just be adjusted with your fingers. If you push up against the spring however, it will empty the fuel in the carburetor bowl all over your hand (it wouldn't be a bad idea to empty the bowl just in case there is water sitting at the bottom).