gas gauge fluctuates 98 3100 lumina

[1979lee]

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

TANK ADDITIVE.

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

deposits."

 

 

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.

 

 

thnaks

[alec_b]

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.