How Does the Crossover System in the Fuel Tank Work?

Discussion in '2005+ Mustang GT 4.6L Tech' started by 07 Boss, Sep 24, 2012.

  1. 07 Boss

    07 Boss forum member

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    I need to drop my tank to check out an issue I'm having. Since installing my GT500 dual pumps my gas gauge gets to just above a 1/4 tank and then drops to empty and the message center goes to 2 miles to empty. I actually ran it out of gas to see if it was just an issue with the float or sending unit. When I fill it up it only takes just over 10 gallons. This tells me that there is another 4 gallons sitting in the passenger side that won't cross over to the pump side.

    So I guess my question is what do I need to look for for a solution to this problem? Besides the one end of the crossover tube that I connected to new pumps, what else should I be looking at? I mean what does the other end of that tube look like or connect to. I'm assuming through my symptoms that the pump drains the driver's side, and then when that side is empty, it pumps the fuel over from the passenger side and then it gets picked up by the pump. Is this correct? Or does it pump it directly from the passenger side right into the line going to the motor? How does it know when to pump it over to the drivers side?

    Just looking for some knowledge on how this saddle tank set up operates so I know what to look for or how to troubleshoot it. I'm gonna drop the tank this week to fix it since I'm not working this week and it is finally dropping below 100 for the first time since forever.
     
  2. JeremyH

    JeremyH 3V Fuel Guru S197 Team Member

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    It's just a a venturi siphon. Passenger side empties first, the siphon on the dirver side just pulls the fuel over to the driver side while the pump is running via the crossover tube in the tank. The passenger side has a level sender that reads from full to 1/2 tank. And the driver side reads from half to empty.

    Passenger side looks like this. On the back side the crossover tube connects to it to draw fuel from the bottom.
    [​IMG]



    Then the crossover tube hooks to the fuel hat on the driver side where the venturi siphon is built in.


    I seriously doubt there is an issue with the passenger side, since you jsut replaced the drivers side that liekly where your issue is. Make sure the crossover tube isnt kinked and that there is a good connection.


    BTW, dont drop the tank there are 2 access holes under the back seat and you can get to everything.


    Guys have had issue with it getting kinked or not conencting properly after a fuel hat swap.

    http://www.s197forum.com/forum/showthread.php?t=88420&highlight=crossover
    http://www.s197forum.com/forum/showthread.php?t=88420&highlight=crossover
     
    Last edited: Sep 24, 2012
  3. 07 Boss

    07 Boss forum member

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    Thanks Jeremy. Awesome post. I think I'm gonna drop or at least lower the tank anyways because those access holes don't line up very well. Pretty stupid of Ford to put those holes off center like that. I think that's how I might have effed up the crossover to begin with. Having to angle and massage the fuel hat in there I'm surprised I didn't screw up anything else. Pretty lame design IMO. Plus I can always swap out that upper arm mount while the tank is lowered. Thanks again Bro.
     
  4. JeremyH

    JeremyH 3V Fuel Guru S197 Team Member

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    Undo the rear torx bolts on the tank strapes, that will let the tank drop a few inches and align the holes alot better, makes it super easy.
     
  5. 07 Boss

    07 Boss forum member

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    Cool, that's what I think I'll do. I wasn't looking forward to unhooking the driveshaft and exhaust. I'll keep you guys updated on what I find. I suspect the crossover tube has either come off or has a kink in it.

    Also does anyone have a pic of the proper orientation of the pump in the tank? I never paid attention when I pulled the stock pump out and replaced it with the dual pump. It could be that it is twisted a bit and causing the tube to have a kink in it. Or if no pic at least tell me which direction the wiring harness or fuel outlet faces. Thanks.
     
  6. Back@itagain

    [email protected] forum member

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    Float arm towards the center of the car and the fittings on the hat face outward towards the driver side windows.
     
  7. 07 Boss

    07 Boss forum member

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    Dropped the tank and pulled the pump. Looked down into the tank and found some parts just laying there I between the baffles. Apparently while squeezing the we pumps through those well aligned holes I must have knocked off that little white tube. The top of that thing attaches eventually to the crossover tube. So problem solved. And to anyone doing a pump swap' dropping the tank a few inches made a night and day difference in the install. About 4-5 minutes as opposed to the 10-15 minute curse filled frustrating install the first time.

    Thanks guys.

    [​IMG]
     
  8. JeremyH

    JeremyH 3V Fuel Guru S197 Team Member

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    :beer:
     
  9. crownaviation

    crownaviation http://www.tudyno.com/

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    Cant tell you how much I hate that STUPID FREGGIN white tube. About as good a desing as the access holes imo.. :mad2: Welcome to the club