I have a 10 year old Craftsman riding mower with a 19.5 hp twin cylinder Briggs & Stratton engine. This mower will run from a cold start for about 15 min. and shut off. It will restart and run, sometimes for less than a minute, and sometimes 10 or 15 min. I have changed the air cleaner, spark plugs, fuel filter, cleaned the carburetor, changed the gas and added fuel treatment. I have checked the gas cap vent for an obstruction and checked the fuel lines. I have even ruled out the dead man switch under the seat, it will die even when the parking brake switch overide is set. When it is running, it runs perfect. What else is left?

When the mower dies, pull the plugs and check for spark, as the motor heats up the ignition coil which creates spark could be failing. If you have a good blue spark then it sounds like you may need to rebuild your fuel pump which is located on the front of the carburetor.

When the mower dies, pull the plugs and check for spark, as the motor heats up the ignition coil which creates spark could be failing. If you have a good blue spark then it sounds like you may need to rebuild your fuel pump which is located on the front of the carburetor.
I can pull the choke when it tries to die and it will ty really hard to stay running, but eventually dies. Does this rule one or the other out?