2013 Mercury 20 Gas dripping out mouth of carb.

[Venomous]

Hi All, Working on a Mercury 20 Outboard for a friend. Carb was originally leaking out the overflows. Rebuilt the carb and now float valve is closing properly and no gas leaking from the overflows. When you try to start the motor, after a second or two of the motor turning over, gas starts to drip out the front mouth of the carb. If you hold the throttle open it will start, but gas continues dripping out the mouth of the carb. I have taken the carb apart again. And everything seems to be in great shape and working properly. We even bought a new carb and it does the same thing. Any ideas? Thanks for any help.

 

[Venomous]

2013 MERCURY 1F20201HK 20M 4S 20 . I put the carb on the bench and hooked it up to a 3-4 psi electric fuel pump. With the fuel pump running it did not leak any fuel at all. After the test the bowl was filled with fuel. So I know for sure the float valve is working properly. I am guessing that while starting, the vacuum going through the carburetor is sucking in to much gas? Maybe? But I don't see why it would do it on the new carb also..