RE: os 46fx..need serious help
If your engine cuts out clean after a short period, then it's either too lean, is getting vibration-induced fuel foaming, or there's something that's stopping the fuel flow.
Fuel flow can be stopped if there's a crack in the fuel line inside the tank that is unported when the fuel level drops to that point. Also, many times, the fuel-feed line to the engine is accidentally attached to the vent line. When the engine's used a bit of fuel, the level drops below the ventline's outlet port. Presto! No fuel.
The way to check if it's the engine, is to put the engine on a test fixture with everything in the open. You can double-check all the fuel lines and make sure there are no problems. If the engine will run "all day", then the problem's somewhere in the installation, and not in the engine, itself.