Small Engine Troubleshooting Problems? Ask a Mechanic Now.
I will assume this is the twin engine?
Engine shuts down for lack of fuel or loss of spark.
Check twin for oil pressure switch that can kill spark.
Next check the solenoid in the carburetor. If it does not stay open, it shuts the fuel off to the engine. Best test for it, is to remove it and plug the hole.
Solenoid has to open as soon as the key is turned on , and has to stay open to keep engine running.
You can hear the solenoid click when key is turned on. Listen for the click. When engine dies, listen for the click as you turn key on and off. No click, no fuel!
If this was a single cylinder engine, the coil could be failing. You would lose spark.