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  1. #1
    Lurker 1979lee's Avatar
    Join Date
    Jun 2006
    Thanked 2 Times in 2 Posts

    gas gauge fluctuates 98 3100 lumina

    my gas gauge fluctuates really bad these days.
    if i fill the tank more then 1/2 full it goes wackojacko.... like max full to 1/2 and back again then jiggly jiggly. i figure its fuel sender time, i did add some Chevron Techron Concentrate Plus, it said it can help this problem, but it didnt......

    the cars always had a funky gauge like never going all the way to full (almost but not all the way).

    now i did swap to a tach gauge cluster a few mths ago, no idea if thats the problem or not, it came out of a 97 montecarlo my lumina is a 98 base.

    i found this .

    GM has just issued a TSB
    on this problem that applies to ALL GM vehicles and
    blames the high incidence of sending unit failures
    on high levels of sulfur in gasoline. The sulfur
    corrodes the sliding resistor mechanism and
    produces erratic and inaccurate gauge readings. To
    address this problem, GM has released a FUEL
    According to GM TSB #06-00-89-07BB, you should
    purchase a bottle of GM Fuel System Treatment
    Plus (part #88861011 for GM brand, 88861013 for
    AC Delco brand, and 88861012 in Canada) and add
    it to your tank at every oil change. The additive
    cleans the sulfur corrosion from the sending unit
    and prevents new corrosion by laying down a
    protective film. The additive also removes engine

    the gm stuff is like $30 ?? way to much , so i went with the chevron additive. Obviously it didnt work... got it at pepboys on sale for $5.

    1997 Chevrolet Lumina
    Bulid Date March 18, 1997
    As Of 6-26-2015 90650 miles
    3400 Tb
    3800 Catback Exhaust
    Maf Screen Delete
    Impala Strut tower brace. Ltz Seats

  2. #2

    Join Date
    Jan 2010
    Minneapolis, MN
    Thanked 77 Times in 65 Posts
    My '96 monte is the same way... the problem isn't really the sending unit or the gauge it's just the fact that the gauge reads too fast. The fuel moving around in the tank constantly makes it read funny. Now, yours seems worse than mine and you're probably at the point where replacing the sending unit is the only (partial) fix.

    Lots of GM cars and truck came with an external "buffer" module that even the dealer won't acknowledge is actually in the car. It slows the response time of the fuel gauge to keep it from bouncing around all the time, yet as far as I know never was installed in a W body of our vintage. I'd start with unfortunately dropping the tank and replacing the sending unit, then seeing how well your gauge reacts. If it gets better, then be happy and move on. The gauge will probably still bounce around with acceleration, braking, and cloverleafs, but at least you'll have a somewhat accurate representation of how much gas is left.

    For the record, mine only seems to read correctly when I'm in motion. It reads lower when stopped, a lot higher then accelerating, but at a steady cruise I get a pretty stable reading and that's the level I go with.
    1991 Buick Regal GS - 121k - 3800 SI - 440T4/4T60 - White/Silver Two-Tone - Grey Sport Interior *DEAD*
    1991 Chevrolet Lumina Euro 3.1 - 116k - 3.1 - 440T4/4T60 - White - Blue Interior *SOLD*
    1997 Chevrolet Monte Carlo LS - 180k - 3100 - 4T60-E - Torch Red - Grey Interior *TRADED*
    2002 Pontiac Grand Prix SE - 195k - 3100 - 4T65-E - Teal - Charcoal Interior *SOLD*
    1993 Chevrolet Caprice Classic - 189k - 5.0 - 700R4 - Maroon - Maroon Interior

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