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Best Way to Ground Fuel Tank

Discussion in 'Early CJ5 and CJ6 Tech' started by scarecrow, Apr 14, 2009.

  1. scarecrow

    scarecrow Member

    OK, new tank, new sender & new gas gauge. Needle pegs @ full.:( OHM reading on sender wire is only 2 ohms. When I put the tank in I upgraded to a ’78 unit with skid plate. When I installed I used bed liner spray on bottom of tank & skid plate to prevent rust. Now I’m thinking that the tank is not properly grounded as the tank attaches to skid plate… question is if I want to ground the tank where is the place to attach a ground wire. Does it have to be on the sender unit or just the tank itself.:?
     
    scarecrow, Apr 14, 2009
    #1
  2. Patrick

    Patrick Super Moderator Staff Member

    Is the sender held in with a lock ring? Well, either way, I'd think the sender would be grounded to the tank. You could check it with an ohm meter. Just ground the tank.
     
    Patrick, Apr 14, 2009
    #2
  3. timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    First thing to do is to test your theory. Run a clip lead from the sending unit to a good ground on the frame and see if your gauge works.

    I wouldn't bother to ground the tank - sender-to-tank is just one more connection to corrode and fail. Instead I would solder a wire to the top of the sender and ground that to the frame. Whether you ground the tank or the sender, it's the same circuit ... you need a return path for the electricity from the sender.
     
    timgr, Apr 14, 2009
    #3
  4. Patrick

    Patrick Super Moderator Staff Member

    I was just thinking that the lock rings are tight enough that it ought to have good continuity with the tank, and the tank is much larger and might be easier to ground to the frame. But yes, might as well test it first either way to make sure the gauge is gonna work.
     
    Patrick, Apr 14, 2009
    #4
  5. bkd

    bkd Moderator Supreme Staff Member 2022 Sponsor

    ran a ground wire on the sender to the frame on mine......as already suggested soldered to the sending unit and a self tapping screw into the frame.
    Jim S.
     
    bkd, Apr 14, 2009
    #5
  6. scarecrow

    scarecrow Member

    Now It's Getting Weird Re: Best Way to Ground Fuel Tank

    Tried grounding tank, no change...Heres where it gets strange, reading taken at sender is perfect 150 ohms (about 4 gallons in tank) Put a new wire & connector on sending unit & I get 2 ohms at the wire no matter where I attach the other test lead, except for the one body mount bolt near the tank. What could be so special about this one bolt:? Also I'm running steel braded fuel lines that run along the frame rail near this bolt, any possible conection:? I'm at a total loss here:(
     
    scarecrow, Apr 14, 2009
    #6
  7. scarecrow

    scarecrow Member

    I think I found the problem. Sender has two posts. One is a screw post with an insulator between it and the tank. The other is a tacked on tab directly to the sending unit. So I grounded the wire that attaches to the tab & ran the other wire to the guage. Needle now reads empty instead of pegged at full. 15 gallon tank only about 3 gallons in it. Hopefully when I add more gas the needle will move.
     
    scarecrow, Apr 16, 2009
    #7
  8. Patrick

    Patrick Super Moderator Staff Member

    AH!
    It'll work now.;)
     
    Patrick, Apr 16, 2009
    #8
  9. ferretjuggler

    ferretjuggler New Member

    The tank don't need to be grounded at all- lots of modern cars have plastic tanks- try to ground one of them!

    You should be able to get the sender working out of the tank with the ground wire and sender wire conected to it, just make sure the hole in the tank is well plugged before you start playing with live wires
     
    ferretjuggler, Apr 17, 2009
    #9