Prior to my fuel level sensor (sender) failing, my gas gauge would swing back and forth whenever I accelerated from a stop or braked to a stop. Eventually, after months of this, the sender failed.

Am I correct in that there is some configuration within the fuel tank, ie baffles, that create a stilling well for the sensor (sender), or does the sender itself have something inherent in its design that usually prevents it from being influenced by the gas in the tank sloshing back and forth?

If the sender depends on baffles in the tank to 'still' the gasoline level, is it reasonable to attempt to repair this, or should I just move towards replacing the tank.

If the sender design incorporates some feature that dampens its motion, is it reasonable to attempt to repair this?

And this is an 87 2.5L,

Regards
Bill

The sender is just a float on an arm. Last time I had mine out I did not see anything on there that would do anything to dampen the movement. So far as I know it's all down to the baffles in the tank.
As for repairing it, probably easier (and safer) to get another tank.

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Anything I might say is probably worth what you paid for it, so treat it accordingly!

Dave

www.ltlfrari.com

Thanks Dave. Baffle problems appear to be unusual as I saw few results in searching thru the archives. Dropping the tank should prove conclusive.

Not just Fieros. I see a lot of baffle failure in older tanks. Most of the time it is from bottoming out, normally on snow. The tank will pop back into normal shape and the damage would not be seen.
The baffle does not stop the sending unit from moving, just slows it down. Otherwise it would also cause a restriction of fuel. Movement is normal. Many manufactures slow the response of the gauge's needle to help with the movement.
The biggest problem with a broken baffle is when it migrates around and pushes the sump off the bottom of the tank or knocking off the sump.
It is better to replace the tank. In Fieros, the front of the baffle has a stand from the bottom to the top to keep it up against dimples in the metal. The stand breaks and the baffle moves. Normally forward, pushing the pump, sump and sending unit off the bottom. Mine was pushed up enough to "run out of fuel" at around a 1/3 tank.
Not able to afford a tank in decent shape, I removed the pump assembly, pushed the baffle back into position and used hose clamps on the filler and vent tubes to keep it in place. (try that with one hand) Of course this was after emptying and cleaning out the tank. With parts and tools in the tank. Only enough room for one hand. Using sense of feel to do the job. Used a small phone to take pics, as I was progressing, to make sure things were right. Very much a P.I.T.A, but worked. Would not recondmend for someone unless they do a lot of work with their hands in small places that you can't see.