Bob's Studebaker Resource Website
Studebaker Avanti Gas Tank
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The older sending units are little more than resistance wire with a sliding contact to pick up the voltage. With time (as with any sliding contact / various metals) the metal corrodes (moisture in the fuel/tank) and the contact point on the pick-up wears down causing erratic or no readings. A few folks have had luck removing and cleaning the contact and resistance wire with electrical contact cleaner (Radio Shack or a better auto parts store) but the time involved in removal / replacement of the sending unit makes this a spotty proposition at best (especially since the brand new sending unit is less than $30 at my local Stewart Warner distributor (don't know where you live but the S-W website lists distributors in most states). Watch out with the sending units...many vendors still have stock on the older res. wire type and will happily sell them to you without mentioning that Stewart-Warner's newest designs are all of the "thick film" variety (no more wire / copper contact to corrode / go bad) that are far more durable especially with ethonol containing fuels! Also, quite often the bad reading is caused by a poor ground connection to the sending unit itself (often the action of removing / replacing the sending unit "cleans" the ground path / connection when the unit is tightened down leading to the conclusion that the new sender solved the problem when, in fact, the simple act of scraping the ring terminal faces and screw to mounting plate or tank threads is what REALLY solved the problem).
When re-installing the sender folks often coat (intentionally or not) the screw / tank threads with gasket sealer in an effort to "make sure the sending unit is sealed to fume / fuel leaks" thereby creating an insulator in the ground path. Make sure the little copper washers for the mounting screws are all present and accounted for (new ones only...they are a "crush" washer!). |