There is no way to bleed a line from the car but usually you dont get issues with air in the lines as long as theres no excess of line to trap the air in. In theory the petcock should bleed out the fuel lines naturally as long as there is significant fuel pressure from the tank. I would see your issue more often when I was getting low on fuel and the petcock would catch the fuel as it sloshed about in the tank. If this makes sense then you could just need a more full tank but if that's not the problem then I'm not sure. There's also the possibility of an issue with the carb or the fittings being loose.
