Past posts about the In and Out fuel system vent valves.

I guess the Out valve failed and due to high outside air temps, pressurized the engine with fuel through the carb return line.(line popped off flooded the hull also)

No hisss when removing the fuel cap for some time.

I replaced both valves now when taking off the fuel cap, it hisses as designed.(relieving the pressure)

Starts right up-no choke-runs great.

Hope this helps someone.....