My lawn tractor won't stay running

Check all the safety interlocks - seat switch ; deck/blade engage ; maybe others .. It helps to have the electrical schematic. .. and a multi-meter. Post the year, make, nodel maybe someone has knowledge. Perhaps something seized or jammed in the drive-train ? but the engine would struggle & stall rather than die suddenly. John T.

Yes, at least if you released the brake slowly, the engine should show evidence of bogging down before stopping, if something is jambed in the drive. Seat interlock would be my first thought.

The seat interlock is where I would start looking also. The mowers I have used will let you put on the brake and get out of the seat. If the break is not on, the motor will stop when you get out of the seat.

I much prefer the system on my old rider - the seat interlock only shuts it down if the blades are engaged. As far as I can tell there is no interlock on the brake. I guess it could possibly roll away on a hill but the hydro transmission wouldn't let it roll very fast - more likely that the hydro would creep it along if not fully in neutral. John T.