not trying to be a smartass, but what makes you think that its the carb? From my experiance that type of problem usually is a fuel pressure problem. I have never run a fuel pump, but can an improper functioning fuel cap, which isn't letting gas tank pressure to bleed out, push fuel past the fuel pump? Is the return line still properly hooked up if needed? To what I know with the power valve issue the only time I have blown one is when the motor has backfired and that has never to my knowledge let fuel to keep flowing down the cylinders.