Fuel Pump Failure?

[67Mach1]

Question, can a fuel pump fail in a state that it will allow too much fuel to pas through and flood the carb? Or do fuel pumps fail only in that they quit pumping?

Using a new rebuld QuadraJet from Oreileys, she ran fine at first but it was blowing black smoke. Very rich, so rich it is fouling the plugs. So here is the problem, I turned the screws down all the way to close and it still idles fine. In fact a bit high and only chokes down when I cover the butterflys with my hand.

Last night we checked the timing, pulled and cleaned all the spark plugs and then put a good used Edlebrock 600 CFM 1405 carb on it. She ran for all of about 5 min or less and then flooded, Gas was coming out of the carb.

We tried to crank it a few times then hydrolocked the motor with so much gas. After opening all the plugs to let the presure out we disconnected the fuel line and cranked it over more.

Any Ideas?