1. 1058077

    I'm a new member and I was hoping I could get a little help from some wiser; more experienced 4 wheelers. I have a 1987 YJ with a 4.2 straight 6, with 188,000 miles on the poor thing. I have replaced most of the whole transmission parts (from the clutch to the actual transmission itself), and I have just recently noticed that my gas gauge has not been reading correctly. Instead of reading full or half a tank, the needle sways back and fourth constantly. The only time when it is not moving like that when I am either at idle for a little while or when I have just filled it up w/a full tank of gas. I think it may be the float, but I have never experienced this problem and don't know too much about gas gauges in general and the whole setup involved. Any advice would be AWESOME! Thanks....peace [addsig]

  2. #2


    Sounds like mabye the baffles inside your tank have come loose. There are walls throughout a gas tank (called baffles) with holes in them to prevent your gas from sloshing around when you drive. But who knows, it could be something else like the float as you said.[addsig]

  3. #3


    that sounds about right...

    Older jeepz such as old cj's and yj's are notorious for crappy gas tanks..

    I think there are only about 4 cj's on the planet that still have a factory gas tank and a working fuel guage, and they are all in the smithsonian :-D

    Seriously tho... The baffles make sense, so does the float. The sending unit is also highly prone to failing on non-metallic tanks, as the grounding apparently goes to pasture...

    Best solution? Replace the tank!
    yep, it sounds drastic, but it works and it STAYS working.

    The only thing to take into consideration is the SIZE of your gas tank. Most CJ's and YJs have HUGE tanks. Whren i had mine replaced, they accidently ordered a 15gal...
    So i loose some gas capacity... who cares, i'll just carry jerry cans on really LONG trips 8-)
    \'82 CJ-7 - AMC 258 -
    Mods: Weber Carb, Borla Catback, Juicebox TFI, 31\" BFG AT, Powermaster 150a alternator, H4 headlights, blazer heater motor conversion, WORKING gas gauge.
    Now with 80% less rust!!!

  4. #4


    It sounds like a bad/ loose ground or gauge. If it was the sender in the tank, gas wouldn't move that drastically to make the gauge needle sway (Maybe a tiny bit), and if it was a baffle, you should be able to hear it banging around in the tank. (I'm not sure if there are baffles in the plastic YJ tanks) Try this. With the key on, have someone rock the Jeep while you sit inside and watch the needle. That should tell you if the sender/ float is sloshing around. If that doesn't show anything, find the wires thet run to the tank and wiggle them while watching at the gauge. Last is tap the gauge to see if it might be a bad gauge. The key is to recreate the problem and that will tell you what to fix.[addsig]

  5. #5


    No Limits I have an 87 also. We have mechanical guages in them not electric ones and thats just the way they act. Mine is actually out of gas at a 1/4 tank so be careful how low you run it.[addsig]

  6. #6


    These guys pretty much have it tacked down but I just replaced my float on my 1988 yj 258 because when I would hit bumps or drive it will bounce back and forth, so I dropped the tank and found out that it was just the float under a 40.00 fix .... [addsig]
    NEED A TRANNY FOR A 1988 YJ 4.2.....HELP

  7. #7


    Good call, I forgot to note my info was based on our 1989Yj
    and I was not aware of the 1987 difference.
    Once again, this shows forums work.
    Enough people chine in and we get the help we need.
    We all have some knowledge about the years we have and together were unstoppable.
    Thanks to all.[addsig]

  8. #8


    If you replace your guage be carefull what one you get, yj's used 4 different ones. You have to take an ohm reading when you have a full tank to get the right one. been through this problem, someone took all my guages when I first got mine. Went through 3 different ones till I got the right one. 8-) 8-) :-x :-x

    edited by: monsterrd, Mar 05, 2003 - 05:32 AM[addsig]
    Still crazy after all these years !!!!!!

  9. #9
    Join Date
    Oct 2002
    East Tennessee


    I think Jeep did this so we would have something to gripe about! hehehe Mine would not work all I did was open the gauge cluster to work in the dash a whaile back now mine is working fine. Then I changed the tank and have all new problems. Always something! tug[addsig]

  10. #10


    it seems that everybody has this problem at one time or another. I just reset my trip-odometer and make sure that I get gas at around 200 miles. Logic: if it's the sending unit, the float, the baffles, the tank... then it's gonna happen again. Save your money and know how many miles you can get on a tank. :-P [addsig]
    89 YJ 2.5L, 4\" Hell Creek Susp., .5\" homemade lift shackles, 33x10.50 on TJ Grizzly Alloys, Herculined tub, K&N, Dynomax Super Turbo Muffler, Russell extended stainless brake lines, & a Congo Cage w/ Yakima bars

  11. #11


    I used to have a very erratic needle on the gas guage in my old '88 YJ. Tapping it with my finger would help,some, and my fuel level was usually right in the middle of the bounce range.

    To fix mine, I had to pull apart the guage cluster. Cleaning the guage contacts on the wiring mat usually fixed the problem. I had replaced the sending unit with no help, that was not the problem.

    No need to replace the tank, anybody actually have a problem with tank baffles in a YJ?[addsig]

  12. #12


    not me... :-D [addsig]

  13. 1058591

    Mine started to do the same thing when I messed with me parking brake a while back. I think it was a ground becuase I took it it for a recall on the parking brake assembly and now it works? Go figure. Just for safety though I would carry a gas tank with you. I can go about 215 miles with 33's and a 4.5 lift. I intend to replace the tank and the sending unit and put a real skid plate underneath. Good luck [addsig]

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