20c is a little light, but that’s nothing to do with a flameout. Once it’s running it will be happy with a 1c pack!
when it stopped was there a white smoke trail? If so, it was fuel supply and could even be a pump issue. So many possible things, but first is the external Kero line full of fuel to the keroplug? If the line is not sealed onto the nipple with lock wire there can be a length of air in the line and at pump start voltages it will take a long time for fuel to reach the Kero plug unless you prime the line first.