Fuel Fuel tank sensors question

Discussion in 'SN95 4.6L Mustang Tech' started by nine2oneGT, Feb 2, 2013.

  1. I have a sumped fuel tank to run with my A1000 system on the car. When I removed the tank to get the sump welded in I had a HELL of a time removing the sensors in the top of the fuel tank. Damn near impossible to do without breaking them, which I did. When I installed the tank I bought a new Fuel tank vapor valve but could not find the other sensor anywhere (not sure of the exact name, or function). It is the one closest to where fuel pump opening is, it is longer then the vapor valve.

    I talked to my tuner and they said to just plug the whole to get it tuned, would only affect filling the tank. I do have a hell of a time filling the tank, I have to fill it with pump barely open so the fuel does not shoot out of the filler neck. Now when I fill the tank all the way I get fuel shooting out of something at the top of the tank. It is very concerning.

    Was wondering if any of you guys knew what the name and function of that other sensor is. I believe it is what is causing my filling and leaking issue. Thanks for the help.

    Here is the vapor valve I currently have: http://www.latemodelrestoration.com/item/LRS-9593B/2000-04-Mustang-Fuel-Tank-Vapor-Valve
  2. The sensor on top of the tank is the tank fuel pressure sensor (FTP). IMO, a bad FTP sensor will not cause slow filling problem. A bad FTP will cause EVAP related DTC codes.

    IMO, there is a blockage in the EVAP vapor recovery system and that is what is causing the slow re-fueling. Check out this thread my thread. My problem turned out to be a blocked charcoal canister.

    IMO, in your case, look for something wrong with the new part or how it was installed. But remember that a blocked vapor line could create the same issue.

    You may also get some relief by drilling out the vent restrictor like I did. As a reminder this option only works for the 1999/2000 MY. The 2001+ has a slightly different gas tank vent design.

    nine2oneGT likes this.
  3. Mine is a 2000, so I will definitely try drilling out the vent restrictor. I can only imagine that the fuel is coming out of the vapor valve. I did not have the spilling issue until a couple of weeks ago, so it is a bit confusing. Hopefully this quick fix will take care of both issues.

    Right now I do not have the vapor valve hooked to any hose, any idea where that should be connected to?

    Thanks for your help wmburns!
  4. I am honestly having problems trying to figure out exactly what the state and symptoms are. It's not clear to me if gas is flowing on the ground or blowing back up the filler neck.

    Regardless, you should rule out the possibility that the new part has been installed in the wrong location (there are two places on top). Or the valve is not working as designed (open when it should be closed or closed when it should be open). Or a vent tube is blocked.

    Also note, that the design of the system is to allow gas vapors to vent but NOT allow raw gas to get into the EVAP lines. Why? Because raw gas will ruin the charcoal canister. The gas turns the charcoal into jelly thus blocking the flow of vapors. No vapor flow, no tank venting.

    Bottom line is that Ford usually doesn't do anything for no reason at all. IMO you will continue to have problems until everything is restored back to a "factory state".
  5. Gas is flowing out of both as of now. If I fill too fast it comes out of the filler neck, when the tank is full it is released out of the vapor valve (I assume). Drips down the sides of the tank and onto the ground. Im almost positive that I put the vapor valve in the same location, probably not working correctly due to incorrect setup without any lines connected to the valve.