There could be several factors, but if it will start and run for a while then the most common reason for stalling out would be some kind of fuel or incoming air restriction. . The exhaust and engine would seem okay since the unit will run if you supply the fuel.
If manually adding fuel, by priming or adding some through the carb or spark plug hole, keeps the engine running relatively normally rather than stalling then it will further confirm restriction of the incoming fuel or air.
Check the air filter or try running without it to see if the problem might be an air restriction.
You can check fuel flow from the gas tank simply by putting the fuel line that normally goes to the carb into a can and turning on the fuel to confirm it flow freely through the line. If not then there is something blocking the line or tank outlet or possibly the tank is air locking due to a plugged vent in the cap.
This model uses a pressurizer system as a prime. That means when you pump the primer bulb it actually pushes extra air into the carburetor float bowl where the added pressure pushes extra fuel out into the air stream through the carb. So if there were any leak or problem with the prime it could be causing an issue.
That leaves the carburetor as the most likely problem area. Possibly some residue of fuel left in the float bowl has caused your float assembly to stick or is blocking one of the small jet openings. So the carburetor may need some attention or repair. We recommend carburetor work be done by a professional to assure the unit safely runs to its full potential and still meets all emission standards.
If you still are having problem then you might need to go back to engine basics as you might have something overheating, such as a coil, or some other issue. The basic troubleshooting in your
and in the link below should help further.