When the P/V is blown the fuel in the bowl will drain into the engine. It'll be hard starting after being shut off for a short time, say 10 mins to a half hour or more. The engine will be flooded and require WOT to fire the engine. IMO take care of the back-fire problem rather mask the problem with a back fire protection valve. I do not like or use these valves as they can cause problems themselves by reducing P/V response or sticking causing the P/V not to work at all.