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  1. #1
    Seaman
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    Default HOW to remove old gas from internal gas tank

    this may be a silly question, but what is the best way to remove the old fuel from an internal fuel tank.

    my boat has a 66 alluminum gallon tank and i suspect the fuel is bad, probably with lots of water in it.

    i am looking to remove about 25 gallons and using the old fuel (MBTE) in my mower. and then filling up with E-10 fuel.

    question:
    1) should i run a tube in from the gas cap on the side of the gunwale to the tank OR

    2) run a manual bulb primer line vs. a mouthful of gas from the fuel/water sep. at the stern and that empty into a fuel can?

    clearly, the boat needs to be pulled out of the water to get below the tank for siphoning..

    i have heard that their is a valve in the gunwale side that may stop the hose from going all the way into the tank.

    any suggestions??

    thanks in advance!!
    dualie

  2. #2
    Chief Petty Officer gewf631's Avatar
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    Default Re: HOW to remove old gas from internal gas tank

    Depending on where your tank is located, you should have an some access point to get to the fuel guage sender. I'd remove the sender, and use that spot to drop your siphon hose.

    25 gallons is quite a lot, so this will give you a large enough spot to drop a decent sized hose, and should also be one of the lowest spots in your tank, so you should be able to get the bad stuff out.

  3. #3
    Lieutenant xtraham's Avatar
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    Default Re: HOW to remove old gas from internal gas tank

    you can buy a small 12 volt fuel pump for about 20 bucks or less from an auto parts store (thats what I use for draining auto tanks) hook it right to your present fuel pickup line, if you have water you might want to closer to the the bottom of the tank, like gew said remove the sender stick the hose in there and pump away.......

  4. #4
    Moderator Bondo's Avatar
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    Default Re: HOW to remove old gas from internal gas tank

    Quote Originally Posted by xtraham
    you can buy a small 12 volt fuel pump for about 20 bucks or less from an auto parts store (thats what I use for draining auto tanks) hook it right to your present fuel pickup line, if you have water you might want to closer to the the bottom of the tank, like gew said remove the sender stick the hose in there and pump away.......
    Ayuh,..........

    I've gone as far as to Build a Transfer Pump this way,.........

    It amounts to an Electric Fuel Pump mounted to a Stick,... With alligator Clips on Long Wires,+ some Hoses.......

    I Just hook it to the Elbow on the Tank, run the wire to the Battery,+ Pump Away..........
    Any Grease is Better,..... Than No Grease at All.......

  5. #5
    Moderator Bob_VT's Avatar
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    Default Re: HOW to remove old gas from internal gas tank

    I have in the past tapped into the fuel line and ran a hose out of the drain plug (in the transom) while the boat is on a trailer. I used a vise grips on the hose as a shut off valve and let the fuel drain into smaller containers. No priming just pure gravity.
    This is a great link to boat specifications http://boatspecs.iboats.com/
    Please, shop iboats first!!


  6. #6
    Honorary Moderator Emeritus tashasdaddy's Avatar
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    Default Re: HOW to remove old gas from internal gas tank

    i remove the sender, hose small enough to go thru transom drain, used oil change pump to get siphon going.
    FLORIDA GATORS
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    Please, NO PM's (Private Messages) regarding boat/engine problems. they will not be answered.
    That is what these forums are for. Post your questions, in the appropriate Forum.

  7. #7
    Petty Officer 1st Class
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    Default Re: HOW to remove old gas from internal gas tank

    One trick I use if you can remove the fuel guage sending unit is attach a stick of copper tubing to the pump. Place the tube in the low spot of the tank and you will pick up ALL the crud in the tank at the same time.

  8. #8
    Moderator Bondo's Avatar
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    Default Re: HOW to remove old gas from internal gas tank

    Did you guys that Siphon the fuel out the drain hole,....
    Change out the Faulty Anti-Siphon Valve while you were Working on them,..??..??..????????????d
    Any Grease is Better,..... Than No Grease at All.......

  9. #9
    Seaman
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    Default Re: HOW to remove old gas from internal gas tank

    thanks for the great advice!!

    i have a 20' center console and a fuel guage, tach, speedometer is on the helm, but i dont' recall an access cover on the deck.
    I must have one right? Otherwise, how else would anyone get access to the sending unit.

    Hopefully, its there- will check tomorrow and post results.

    if its not on the deck, where would one think it would be located??

    Dualie

  10. #10
    Commander studlymandingo's Avatar
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    Default Re: HOW to remove old gas from internal gas tank

    Mine is located under a panel underneath my console.
    The wetter, the better.

  11. #11
    Seaman
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    Default Re: HOW to remove old gas from internal gas tank

    the boat is out of the water and time get going on this project.

    bummer- of course, the sending unit is someplace that is not easily accessible. would hate to take off the helm.

    so that being said, can i pull the fuel from the line that leaves the tank and hits the water/ fuel sep??

    and if so, can i use a bulb primer hose to get it going and then use gravity to finish it off?

    i am concerned about having any type of static or electrical componants near fuel being removed.

    thanks
    D

  12. #12
    Moderator Bondo's Avatar
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    Default Re: HOW to remove old gas from internal gas tank

    "and if so, can i use a bulb primer hose to get it going and then use gravity to finish it off?"

    No,........

    Boat Fuel Tanks have a Anti-Siphon Valve mounted in the Elbow at the Top of the Tank.............

    It'll take Vaccum from a Fuel Pump to Pull the Fuel Out.........

    Ayuh,......
    You CAN mount an Electric Fuelpump to the Line at the Fuel Filter,+ Pump it Out from There.......
    Any Grease is Better,..... Than No Grease at All.......

  13. #13
    Seaman
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    Default Re: HOW to remove old gas from internal gas tank

    thanks again for the great responses.

    i ended up draining the fuel this weekend.
    threw on a bulb fuel line before it hits the f/w separator and let it drain out into several 5 gallon jugs.

    it worked great.
    time to burn it on the mower
    thanks dualie

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