Fuel Filler Tube - What's that little copper looking flap? | Ford Explorer Forums - Serious Explorations

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Fuel Filler Tube - What's that little copper looking flap?

Art Mann

October 3, 2019
Reaction score
San Antonio
City, State
San Antonio
Year, Model & Trim Level
2004 Sport Trac
What is that little copper looking flap supposed to do? It is looks like it is ported to the small vent line that runs from the filler tube mouth down to the tank area next to the main fill hose, Does it have some kind of switch or something.. Mine is in the open position. I remember it used to move up as the nozzle was inserted, but what is its function?


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There is a small rubber seal inside the neck.

The flap closes against the seal an prevents vapor loss from the tank.

You might start getting codes soon.

Ahh .. and shunts those vapors via that tee that the small vent tube connects to which is located under the bed and allows vapors to get shunted back to the carbon canister. Looks like there is a solenoid on that line right before the canister. Interesting. Any ides what that chichadera is INSIDE the fuel tank itself about 4" into the plastic piece that extends from the end of the tank itself and onto which the filler tube main hose is clamped? ( You might surmise that I am trying to track down a slow filling gas tank problem.!!)


At start up the computer opens the tank purge valve and draws vacuum on system. Sensor in line watches this negative pressure reading.

Computer closes valve and watches reading again to see if it falls off. If negative reading rises Computer flags as code of Failed evaporative system check.

Really good video by a really good tech.


let me take a look .. In the meantime , can you give me some direction and understandings based on the attached image? I pulled that hose at the blue connector and thought it should vent and fill correctly. I blew and also sucked air thru the hose it connected to ( into and out of the tank) .. I'm missing something.