Maybe I'm missing something, but it sounds to me as if the carburetor float is stuck in the fully-down position, due to the fuel drying out over the summer and leaving a bunch of gum behind. With the needle right down and a car-type fuel pump, you could just about estimate the fuel pump outlet pressure from how high the fuel squirts up from the floatbowl vent. Hmm, a metre would mean a fuel pressure of 2.2 p.s.i. at the seat (which should be blocked by the needle, but isn't if the needle or float is stuck down). Sounds about right - it's within the normal range for a car fuel pump anyway.
