Re: Fuel Guage 47 Custom Super Clipper

Posted by HH56 on 2015/10/6 19:48:59
With the old Stewart-Warner gauges Clippers used and their resistance range, when the gauge reads full the sender is effectively a dead short to ground or 0 ohms. When fuel level starts going down resistance increases and is 100 ohms when empty.

For the gauge to suddenly quit reading and forcefully drop to empty it would require the sender or wire to go completely open. The gauge has two electromagnets which balance the needle between them. The complete loss of the sender signal would allow one of the electromagnets in the gauge to suddenly become stronger and slam the needle down.

Since all is normal until it gets down to 3/4 tank, if all the connections are tight I would suspect the sender has failed and that the wire portion is OK. The resistance wire in the sender is supported on a curved piece of fiber or phenolic material and I'd almost bet that either it has warped so the wiper looses contact or has otherwise become damaged.

You could do a test by disconnecting the sender wire at the gauge or if your car has one, the thru connector in the trunk and insert a fixed resistor in the neighborhood of 50-75 ohms between the wire and ground. That should let the gauge read somewhere around a quarter of a tank. If all is steady then something vibrating and opening the wire is ruled out and sender is the culprit.

If it is the sender I don't believe there is currently any option except getting an exchange unit from one of the vendors or having yours repaired. The old 0-100 ohms is obsolete and I haven't found any universal senders or other units available in the US that can substitute. There is a sender I found with that ohm range in Australia that may be a possibility but the freight to get that item here is more than the sender.

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