I cant keep gas from coming out of the top overflow valve of my 400m carb. It had new needle, valve and seat a while ago when it started doing this. Recently I rebuilt the whole carburetor and again, put all new components in. I cleaned it inside and out and followed the directions perfectly but it still seems like the float or needle are constantly sticking.

I know the float is free of holes, there is no dirt in the seat or jets, and it is adjusted correctly. I have put tons of effort to stop it from passing the valve but I have no idea what im doing wrong. I took it apart a few days ago, messed with a few things, then put it back together and the gas had stopped coming out of the top. I went out Sunday morning and it was back to the way it was. It is a motorcraft carb from a 400m.

Thanks, any help is appreciated

 

check it in water and see if its staying afloat or slowly sinking. if not, its definetly something in you float to seat system. forgot to mention what is your fuel pressure?