There is sufficient fuel in the carb and fuel lines.
Carburettor engines have a problem with neg-G though. The Spitfire could not pull G above G-1 and this was a weakness exploted by ME109 chaps. they would go into an inverted steep turn or similar move to shake the Spitfires off their tails - the spit could not do this untill a small hole was drilled in the top of the carb (float chamber) to let pressure escape. (Please correct me if I'm wrong)
WF.