See here:
Number 2 in the article linked above (note I said “sustained” in my original reply), a bit copied below.
Extended duration at zero or negative G on the aircraft, particularly while in afterburner places extreme demands on the engine fuel feed system. You’ve seen NASA astronauts floating in an aircraft that is used to simulate zero gravity. The same thing happens with the remaining fuel in the F-14’s fuel tanks. The fuel floats to the top and exposes the fuel lines to air. If air is drawn into the fuel lines, particularly during afterburner operation when there is a huge demand for fuel, the result can be an afterburner blowout or even worse an engine flameout.