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  1. #1

    Default Grounding a fuel tank?

    I have an aluminum fuel tank in my 20' boat. It is 64 gallons. I removed the tank after it had been setting for 7 years. I was going to clean it out really good and get any varnish/debris out, but luckily the previous owner had used E-free gas with stabilizer. Believe it or not, the tank was very clean inside.

    Anyways, before I took the tank out, the fuel gauge worked. Now, it doesn't. When I turn the key on the gauge goes to 1/4 tank, then when I turn it off it will go back to 0.

    I am pretty sure that something changed when I re-installed the tank. I pulled the sender out so that I could see inside the tank, and then re-installed it.

    There is a sender wire and a ground coming off of the fuel tank that also runs to the fuel gauge. But as I recall, those were the only two wires that went to the tank. Shouldn't there be a wire from tank to ground to ground the tank out???? I didn't see any other wires. Here are the two wires that I speak of (figure 4):



    There is an angled piece of aluminum on the top of the tank that I could easily fasten a wire to and run it under the floor and ground to my motor. Should I do it? (Bottom of bottom picture.)


  2. #2
    Join Date
    Sep 2006
    Location
    Baton rouge, La, USA
    Posts
    2,501

    Default Re: Grounding a fuel tank?

    the ground is the wire closer to the edge of the unit...the wire in the middle is the sender wire..the tank don't need a ground...you should read continuity from the black wire to ground...measure from it to any known ground on the boat...the block on the motor is ground for example..Click image for larger version. 

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  3. #3
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    8,201

    Default Re: Grounding a fuel tank?

    The wires appear to be going to the correct leads on the sender....assuming they are clean and solid, I'd be inclined to check to opposite ends, at the gauge. The black lead should provide the return (grounded reference) for the sender unit.

    There should also be two 'bond' wires; one for the fill port and one to the bonding system's 'ground plate'. These are to dissipate any static charge that may accumulate during fueling.

  4. #4

    Default Re: Grounding a fuel tank?

    Thanks guys.

    Mark, I am pretty sure there is a bonding wire at the fill port, but I do not believe there is another one on the tank. The black wire that comes into the sender is continuous with ground, and grounds out the tank as well. Is this not ample enough?

    I checked the fuel gauge and it is functional (with key on I touched the wires and the gauge pegged at F, took them apart and back to E) so I believe that I have a bad fuel sender. That's ok because I want to get a reed style sender anyways as they are more accurate.

  5. #5
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    8,201

    Default Re: Grounding a fuel tank?

    Quote Originally Posted by rotus623 View Post

    Mark, I am pretty sure there is a bonding wire at the fill port, but I do not believe there is another one on the tank. The black wire that comes into the sender is continuous with ground, and grounds out the tank as well. Is this not ample enough?
    There should be a continuous bond wire from the fill port, to the tank, and to ground. I've seen many boats with only the reinforcing wire in the 1.5" hose pulled out and bent to meet the metal on either end as the only bond wire. Its a safety concern....

    Quote Originally Posted by rotus623 View Post
    I checked the fuel gauge and it is functional (with key on I touched the wires and the gauge pegged at F, took them apart and back to E) so I believe that I have a bad fuel sender. That's ok because I want to get a reed style sender anyways as they are more accurate.
    The only other check would be the 1/2 way point - if its an american standard gauge configuration, you can remove the wires at the sender and connect them to either end of a 110 ohm resistor.

    Sounds like you have a good handle on the matter.

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