Gas Gauge Mystery solved, maybe

[Dan White]

Last night I talked to Bob Powell, a retired Stewart Warner engineer that still works on gauges. I had hoped that Bob could look at my gauge and sending unit and get them to work properly (still reads 5/8 to 3/4 when I have a full tank). It was clear Bob's memory was not what it used to be, but two things were clear: 1) He cannot fix Studebaker gas gauges any longer due to not having the right parts. 2) Studebaker did not use a standard 30 to 240 ohm sending unit! I challenged Bob on this but he was certain this was the case, he even used the word "weird" to describe the Studebaker sender (and these were made by S/W so I am guessing he should know). Bob could not remember what the range on a stock Studebaker sender should be, too bad. Anyway, this is probably the reason many of us cannot get a full reading when the tank is full. I would love to know if any one has a NOS or good used sending unit they could actually measure the range of resistance to let us know what it is.

What I have found is that you can "force" the gauge to read full if you bend the float stop and allow the wiper arm to ground out on the sender body. This however is a false reading and will drop to 5/8 to 3/4 the instant that the level drops enough to let the float move off the stop.

If you are going to buy a new sender from SI or other suppliers you will find the new units are not wire wound any longer but use a ceramic thick film and you cannot force the sender to cheat and give a false full reading. These new units are 30 to 240 ohm std. S/W sending units.

I plan to send my gauge and sender to a rebuilder to match the two to get the right readings. However, it now looks like that will be the only solution unless you can find a NOS sending unit.

Dan White
64 R1 GT
64 R2 GT

[GTtim]

About 2 years ago my gage would only read 5/8 or 3/4 like you say. I replaced the sending unit with a new Stewart Warner that I got from Dave Thebault. After some adjusting of the arm in the tank it reads perfectly from full to empty. The only problem was that the unit came with a rubber gasket that failed in a month, after I replaced that with a cork one, there have been no problems.

Tim K.
'64 R2 GT Hawk

[Dan White]

I have new sending units from SI and Champ parts. They are basically the same with the Champ unit having a generic float arm and the SI apparently having one that is custom setup for a Hawk gas tank. (Note that the Champ costs $30 less than the SI!). Both sending units give me 5/8 to 3/4 on both gauges I have. So I don't know what the problem is if it is not a mismatch of the resistance between the sender and gauge.

Dan White
64 R1 GT
64 R2 GT

[gordr]

Dan, are you sure the tank is well grounded? Any stray resistance between the sending unit and ground will limit the maximum gage reading.

Gord Richmond, within Weasel range of the Alberta Badlands

[Dan White]

Gordr:

I have taken the sending unit out and run it right at the dash. I have run ground wires directly from grounds from the cigarette lighter. I have tried about every imaginable way possible to run this setup and still get the same readings.

Dan White
64 R1 GT
64 R2 GT

[starlightchamp]

Could be internal to the gauge. If the gauge is for a 62/63 (maybe others), it has a weird internal mechanism. Two magnetic coils are wired so the current causes the needle to move toward full and a reverse field from the second coil acts like a brake. I have taken my 63 Hawk gauge apart because it would only show half full and then snap to Full. A new gauge fixed the problem but they are RARE.
....Dick