My '99 has a black metal flapper just inside the top of the fuel filler neck. That flapper actuates a little black plastic slider that covers and uncovers either one or both (don't know if it covers one or both) of the openings of the two small metal lines that are soldered/brazed to the side of the filler neck. When a gas nozzle is inserted into the fuel filler neck, it pushes the flapper down and the flapper pushes the little plastic slider up, uncovering the openings to the metal lines. When the gas cap is screwed on, the gas cap pushes the slider back down, covering the openings. (could be visa versa?)
Question: In gutting the fuel filler neck, do you remove only the metal flapper and leave the slider mechanism in place and intact, or remove it all?
If all is removed, then those openings to the two small metal lines are always open.