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Thread: Fuel Gauge

  1. #1
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    Fuel Gauge

    My fuel gauge would bounce around at the 1/2 full mark, I changed the sending unit. Now it sits steady at the 1/4 mark,I ran a wire to the battery and thegauge body but it made no difference. Does anyone have an idea as to whats going on?....Hal

  2. #2
    Super Moderator LarrBeard's Avatar
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    Fuel Gauge Issue

    Quote Originally Posted by Hal Edmondson View Post
    My fuel gauge would bounce around at the 1/2 full mark, I changed the sending unit. Now it sits steady at the 1/4 mark,I ran a wire to the battery and thegauge body but it made no difference. Does anyone have an idea as to whats going on?....Hal
    The basic circuit is a variable resistor in series with the gauge. Less fuel, higher resistance, lower reading on the gauge. More fuel, less resistance, higher gauge reading.

    But, before we can make any better guesses - what Jeep are we talking about? There are significant differences between various models. My '48 truck is a lot different than a CJ 3A.

  3. #3
    Super Moderator LarrBeard's Avatar
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    Gas Gauge Information

    Quote Originally Posted by Hal Edmondson View Post
    My fuel gauge would bounce around at the 1/2 full mark, I changed the sending unit. Now it sits steady at the 1/4 mark,I ran a wire to the battery and thegauge body but it made no difference. Does anyone have an idea as to whats going on?....Hal
    These may give you some ideas to check out:

    https://www.thecj2apage.com/forums/w...opic17875.html

    http://www.cj3apage.com/cgi-bin/3Aya...num=1429482195

    https://cj3b.info/Tech/FuelGauge.html

    I would check out the ground on the gauge case very closely.

  4. #4
    Super Moderator gmwillys's Avatar
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    I concur with LarrBeard on the ground check. The links are great as well!

  5. #5
    Senior Member bmorgil's Avatar
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    [QUOTE=LarrBeard;7831]These may give you some ideas to check out:

    https://www.thecj2apage.com/forums/w...opic17875.html

    http://www.cj3apage.com/cgi-bin/3Aya...num=1429482195

    https://cj3b.info/Tech/FuelGauge.html


    Definitely bookmarking those links! Everything you want to know about the fuel gauge.

  6. #6
    New guy to this forum, but also have a fuel gauge question. Have a '61 CJ5; original fuel gauge stopped working about 6 weeks ago. Put two replacements in, can't get any to work. Also replaced the sending unit. The gauges simply go right to "full", even though the tank is only half full. Don't mean to butt in on Hal's issue, but any ideas? Had a CJ2A owner tell me there's a set screw on the back of the gauge I need to worry about, but I don't even see one and am clueless at the moment.

  7. #7
    Super Moderator LarrBeard's Avatar
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    Fuel Gauge Issue

    Quote Originally Posted by minnesotawillys View Post
    Have a '61 CJ5; original fuel gauge stopped working about 6 weeks ago. Put two replacements in, can't get any to work. Also replaced the sending unit. The gauges simply go right to "full", even though the tank is only half full. Had a CJ2A owner tell me there's a set screw on the back of the gauge I need to worry about, but I don't even see one and am clueless at the moment.
    I'd suggest you read the three links in the email in this link, there is good info about fuel gauges in general there - even though it applies to CJ 2A's..

    The set screw is not there on all CJ 2A repro gauges and I haven't seen any reference to it on CJ 5 gauges at all.

    I'd check and make sure all of the wires are on the right terminals, and that you have a good ground. Here is a good article:

    https://www.morris4x4center.com/jeep...oubleshooting/

    Let us know what you find, we like to know if our advice is any good!

  8. #8
    Many thanks for the advice; I'll give it all a look. I'm not sure a CJ5 has a set screw -- I sure don't see one. I'm thinking, like you, it's likely a wiring problem. Thanks, again.

  9. #9
    Super Moderator gmwillys's Avatar
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    Welcome Minnesotawillys!

    I concur with LarrBeard. I am certain that there is not an adjustment screw on the original gauge. Most of the time, if there is a screw, it is stamped +/- around it for adjustment.

    What part of Minnesota do you call home?

  10. #10
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    I added a ground to the sender unit, replaced the gauge after cleaning the back of the dash around the gauge hole. It turned out to be the float rod was to wide and was rubbing the side of the sender unit hole. Replaced the old sender unit now gauge works fine, thanks to all for your great advice. I couldn't get the panel lights to work properly, turns out they have 12volt bulbs in them. I'm just waiting for the 6v bulbs.....Hal

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