Re: 48 fuel sending unit

Posted by HH56 On 2023/10/27 21:50:21

The 48-50 gauges and senders are unique. The senders have a heater and mechanically biased bimetal on/off contact action. The output is a pulsing action alternating between 6v and ground. The float changes pressure on the bimetal so the time it takes the heater to heat and close the contact for the on/off action varies. No gauges Packard used in the years before or after work the same way as those do. All others were changing resistance types where the float would move a wiper across a resistance wire to change the resistance from the gauge to ground.

As far as I know there are no reproductions, no modern universal senders that will work and NOS senders for the 48-50 models are all but obsolete so somewhat hard to find. You might try Tucson Packards as they sometimes have the odd and hard to find item. If it just needs a new float that can be done but if the case or mechanical parts are severely rusted or something is wrong with the bimetal or heater I don't believe any of the instrument places will try to repair them -- or if there is a place that does good repairs, it is not common knowledge. If no one else has better information, about the best I can suggest is try to find good used. There are 17 and 20 gallon tanks in those years so two senders were used and they are not drop in interchangeable.

It has been reported that some Ford Motor Co products of the same era also used that type of sender but don't believe anyone has come up with a specific car or model to try and find a cross. Last I read Ford people were in a similar fix but since those are much more plentiful there might be some old stock at some of their vendors. If someone has any interchange possibilities it would be nice to see it posted.