Pressure test all carb needles/seats. Needs a WET needle and should hold back 7psi for 30+ mins.
Would think when she was drowning in fuel she would be chugging black fumes out.Funny thing though, the engine wasn't burning black smoke, when the top vent of the carb was pouring gas.
could that be a return line? Late car carburators used them. Do any mowers?
Just worked on my first Nikki - damaged the supper thin "gasket" round the float need tube.Some of the Nikki type carbs have a internal gasket that when it goes bad will allow fuel to BYPASS the needle and seat and flood the carb.
I use a mityvac for pressure/vac but a blood pressure bulb and a low pressure fuel pump gauge can be used
I also install in-line fuel filter and fuel petcock on my own equipment.