sounds like plugged fuel line, from finally agitating enuff junk loose in the tank to pump it - if ya got an inline fuel filter, might be plugged - if ya don't have one then the carb might be plugged - next time it happens, have tools w/ ya to pop top off carb and see if the bowls empty - otherwise
try this one!! - if it's vapor lock, letting it sit w/ hood up for 10 min will clear it, and the pump will be able to work again - skip the mechanic until ya
know what's wrong!!
Bill