am I doing this right?

[krobb]

I am setting up my newly rebuilt weber 40 IDA's so I have them on the bench. I am using a funnel positioned about 6" above the carb and I am pouring gas into it which connects to the fuel line which fills the bowls. I am measuring the fuel level from the handy vial I attached to the float bowls. When I pour the gas in and the float bowls become full, it takes a few moments for air to work its way out and I keep the funnel half full with fuel. I am getting perfect readings since the fuel level is between the top two lines. The problem is when I start pumping the pump jets to measure the amount of fuel being pumped from the jets, the fuel starts overflowing from the top of the float bowl vial which is way past the top two lines that it should be at.
Should this be happening? Shouldn't I be able to keep the vial attached to the float bowl while I test the pump jets? Or should I take the readings from the float bowl level after I pump the accelerator jets a few times?
Is my technique totally incorrect???