This carb leaks out from the fuel bowl into the primary and the throat of the carb. We have replaced the power valve, and overhauled the carb. It runs great but smells of fuel when shut down. I have replaced the charcoal cannister and checked for pressure from the fuel return line and the solenoid, too. Nothting. The fuel bowel is nearly empty when this happens. It is as if some gas is entering the fuel bowel and pushing the fuel out. We even tried a different carb and got the same results. HELP