I have a riding mower with a CV-12 engine. Sometimes it stops as if out of gas. If I remove the gas cap and wait a moment, a stream of bubbles from the fuel line will bubble up through the fuel. Then it will start quickly and run fine.
I don't see what could be getting pumped up with air except the fuel pump. It's two check valves and a diaphragm operated by a nylon lever. The outlet check valve is at the top, so I don't understand how the pump could accumulate air.
Has anyone else run into this problem?