It would be good to know your current hot start technique. Unlike with SU's, which don't have an accelerator pump, frantically pumping the pedal with a Weber, while cranking, has the worse possible effect. Every pump adds to the pool of gas in the manifold. When hot it should start without touching the throttle pedal, normal for SU's, or just a slow push to the floor to minimise the excess gas (Weber) and then crank for a second or so before easing up on the pedal, when it should catch and start.