After adjusting the valves on my 1989 454 LTD, I primed the carbs by putting a vacuum test hand pump to the fuel valve. I flooded out the carbs. Now the bike will run on the fuel in the bowls, but as soon as I open the fuel valve it floods out. I took the bowl off on carb and saw nothing wrong. Any body no what I did to my carburetors?

 

I came across the same situation. I hate to say that you might have damaged the fuel petcock diaphragm by pumping it with a vacuum pump. Or, the diaphragm was bad to begin with. I ended up purchasing a petcock rebuild kit from Ebay, and now all the leaks have stopped and I am no longer flooding the carbs. Good luck!