Sounds like something wrong with the float system inside the carb. The float in your carb works basically the same way the float does in the toilet in your house. Once the fuel level rises high enough it will cut off the incoming supply of fuel until the level drops enough to open the passage again.
You could have one or more of the following problems:
- dirt stuck in seat, this will prevent the needle from cutting off the incoming fuel flow
- worn needle and seat. Trying to seal but can't
- hole in the float itself. If there is a hole in the float it will not "float" on top of the gasoline and prevent the needle from engaging the seat
- poorly adjusted float (fuel level set too high)
Once you get it fixed you should change your fuel filter (you have been doing that all along anyway, haven't you?)
Hope this helps.
'69 SS350, '79 Sport Coupe, '79Z28, coming soon...'70 RS
SOMEBODY PLEASE STOP ME BEFORE I BUY ANOTHER ONE!!