RE: Goldberg Ultimate 10-300 build
animalppp.....................I think you are confusing the KWIK fill fueling valve with the Fuel Dot. They are totally different.
You are referring to the Du-Bro or Great Planes Fueling Valves where you insert a probe into the valve and fuel line to carb is automatically shut off. When the probe is removed, fuel flows through valve to carb.
The Fuel Dot that I am referring to is just one line from the fuel tank, one end goes into the tank, directed down and to the front of the tank the other end is used to fuel up and when fueling is completed you plug that end. It is made by Bisson Custom Mufflers. It's used for fueling and draining for in-cowl engines. Although you can also use the one that you have for in-cowl engines.
The one that you have, has the tendency to leak. The problem that you are encountering is the little spring inside is sticking, you need to change the O ring and spring. There're rebuild kits for those fueling valves. Just watch it, best to replace it. Inserting the probe into the valve can sometimes damage the O ring, and the spring to collapse. I know because I have rebuilt one this season.
Charles.