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Fuel Tank/sending Unit Grounding

Discussion in 'Early CJ5 and CJ6 Tech' started by Rustman, Jan 12, 2020.

  1. Jan 12, 2020
    Rustman

    Rustman New Member

    Charles Town, WV
    Joined:
    Dec 28, 2019
    Messages:
    17
    Working on my 1970 DJ with the rear mounted 10 gallon tank. I have the tank out for repairs (big dent and several pin holes). While it's out I'm addressing the problem where my fuel gauge quit working many years ago. Primary cause was likely the half dozen cracks and holes in the float :) I have a new float and measured with an ohm meter that the sending unit does change resistance as I move the float arm.

    But here's the mystery to me. The sending unit has only the single wire connection. The tank was suspended with two straps and welting (of pressboard) between the strap and the tank and wood blocking above the tank. This all appears OEM. The only tank grounding are two clips that go over the welting and fuel tank strap with a sharp point against the tank. These are described in the parts manual as "Clip Ground" and a quantity of 2. This to me seems a feeble grounding method at best.

    Since I have the tank out for repairs and will be cutting it open this afternoon to replace the pin holed metal and repair the massive dent I wonder if I shouldn't just weld on a tab for a good solid ground lead to the body?

    Thanks
     
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  2. Jan 12, 2020
    Twin2

    Twin2 not him 2020 Sponsor 2019 Sponsor

    Virginia Beach, VA
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    if it was me . I would put a ground tab on sender
     
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  3. Jan 12, 2020
    Rustman

    Rustman New Member

    Charles Town, WV
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    Dec 28, 2019
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    Ron, thank you. That was my other consideration. I'm trying to restore this. But at the same time some things should just be upgraded. As an aside I see you have an Airborne patch for your avatar and your location is VB. Have you been to the Military Aviation Museum in Pungo? I'm down there every year for the Warbirds Over the Beach show.
     
  4. Jan 12, 2020
    Twin2

    Twin2 not him 2020 Sponsor 2019 Sponsor

    Virginia Beach, VA
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    yes and ride by there often on way to NC
     
  5. Jan 12, 2020
    timgr

    timgr Jeepin' Nerd 2020 Sponsor 2019 Sponsor

    Medford Mass USA
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    Yes. Solder a tab for a push-on terminal to the sender top plate. Or solder a wire directly to the plate.

     
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  6. Jan 12, 2020
    timgr

    timgr Jeepin' Nerd 2020 Sponsor 2019 Sponsor

    Medford Mass USA
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    Just to add to this -

    I have two of these guns, and I use them exclusively for car wiring. Works fine for that, despite what Paul here says about what a pain these are for soldering wires. Not great for electronics, but pretty good for 18-16-14-12-10 gauge stranded wire used for car harnesses. Paul recommends liquid flux - that's great for surface mount devices (SMDs) but for car wires, I recommend a small container of paste fllux. Be sure to get a rosin type flux, not acid flux. I have a can of Kester paste flux in my garage that I've used for decades and it's only about half gone.

    Also, if you want one of these guns, you should be able to find one on your local Craig's list for a few bucks. There's a 140W gun on the Boston list right now for $5. Weller sold a lot of them, and most people wouldn't know what to use them for. Swap meets, garage sales, etc.
     
    Last edited: Jan 12, 2020
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  7. Jan 12, 2020
    Wyo Eeyore

    Wyo Eeyore Member

    Eastern WY next...
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    Feb 22, 2006
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    75
    On my 64CJ5 I ran a wire from one the sending unit hold down screws to the body, held with a screw. I crimped on eyelets to the wire. Not fancy but it is a good ground for the tank.
     
  8. Jan 12, 2020
    timgr

    timgr Jeepin' Nerd 2020 Sponsor 2019 Sponsor

    Medford Mass USA
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    Good idea - however, I suspect this sender uses a lock ring instead of screws.
     
  9. Jan 13, 2020
    Rick Whitson

    Rick Whitson Detroit Area 2020 Sponsor 2019 Sponsor

    I live South of...
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    My 64 has screws holding the sending unit in the tank, so I just grounded it to the body, which is grounded to the frame, which is grounded to the battery. Works for me. I don't know when they went to the ring type hold down but I have not seen one on any of the 60's Jeeps I have worked on? Good Luck
     
  10. Jan 13, 2020
    Rustman

    Rustman New Member

    Charles Town, WV
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    Dec 28, 2019
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    Not sure where my reply went, maybe I got distracted and never finished.

    I do in fact have one of those solder guns, I think a Weller, use it for my other hobby of model trains. The tank has a lock ring, not screws. Probably about the first year of that for Jeep. Looking online Chrysler had a similar no ground set up and had a jumper clip from the sending unit neck to the steel fuel line, but the DJs seem to use a thermoplastic line, not steel. At least that's what other DJ owners have seen. So the clip on the hanging strap seems to have been the OEM solution. I guess later it was determined a grounding pigtail should come off the sender. So it looks like I'll just add a tab to the sender. Easy enough.

    Thanks everyone!
     
  11. Feb 21, 2020
    Hônes

    Hônes New Member

    Colorado Springs CO
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    Apr 5, 2019
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    31
    Hey Matt, My '66 CJ has the underseat 8G tank with bolted-in sending unit. I took it out as part of a restoration. Once painted with POR 15 and installed on foam rubber feet to isolate it from the floor pan and seal the holes in the floorboard that the fuel line and drain runs through, the fuel gauge magically quit working. I suspect I've got a similar jumper wire to run. -Hones
     
  12. Feb 21, 2020
    shadetreetim

    shadetreetim Member 2020 Sponsor

    Riverside, Ca
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    Oct 2, 2019
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    The repop sending units have a ground tab on them. Easy to run a wire over to the ground screw in the frame by the taillight.

    In regards to soldering, I do quite a bit of soldering on various projects. My favorite soldering tool I've found to date is the Milwaukee 12V Soldering Iron. No cord to get in your way. Stands up on its own battery. Heats up quick. If it has a con, it's that the battery doesn't last that long if you don't turn it off between soldering task. They're not cheap, but I don't regret the money spent every time I use it.
     
  13. Feb 21, 2020
    BadGoat

    BadGoat How High Can You Climb?

    Northern Virginia
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    Apr 27, 2017
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    253
    I had my fuel tank grounded to the frame but the fuel gauge still wouldn't read correctly. So I ran the ground directly from the sending unit to the gauge and now it works fine. They are fairly sensitive, so going through the body and the frame may not be the best option.

    I do the same thing with all the electronics on my Jeep, either a dedicated wire for the grounds or run a wire to a dedicated bus bar. I have 4 bus bars on my Jeep, one on each front fender, one under the dash, and one in the rear driver fenderwell. I've rewired too many trailers to trust a frame to provide good grounding.

    Mike
     
  14. Feb 22, 2020
    Rustman

    Rustman New Member

    Charles Town, WV
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    Dec 28, 2019
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    Thanks everyone. The tank has been out with a big square cut out so I could access for dent repair. Then I had to travel for work so I haven't been able to finish putting the tank back together. When I do I'll add a Stakon tab to the sending unit. Then a pigtail to the body via a ring connector tucked under one of the bolts for the floor cover.

    Matt
     

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