Beginning last week, my gas gauge needle bounces erratically after the car hits bumps of any significance on the highway. It remains otherwise accurate. This problem is semi-amusing but eventually gets very irritating...

Post script:
I have nothing but praise for this site and its moderators and other contributors. I was disappointed to read "edna"'s reaction (that is, gross overreaction) to Benzmac. It was entirely unwarranted.
Just keep up the great work!

Try to use your hand to hit the left side of
the instrument (ignition key on or runing)
see the fuel gauge needle bounce or not ?
If the gauge dos't bounce it must be the fuel
tank sending unit(in side the gas tank)
On your 86 300e should be in side your trunk
behind the installation. It do require a 46mm
socket to open it.

While it may be the sending unit in the tank, don't rule out the possibility of a wiring problem, such as a bare spot somewhere in the harness. I would expect cornering to have more of an effect than simple bumps, if it was the sending unit, as it tends to make the liquid in the tank slosh around, moving the float arm, whereas the same liquid tends to damp the fast motion causing the intermittent condition. I'd be looking at wiring and connections first. If all else fails, then I'd look at the sending unit itself. Good luck with it.

Don't know what model car you have but sounds like a broken wire at the fuel tank plug connection.

When I first got my '86 300E last spring, I had the same exact thing happen to me....it lasted a month or so...it went away and has never came back! Go figure....

Mike

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1986 300E 138k
MBCA Concours Judge
Board Member -
Western Reserve Section