Re: Gas Gauge flutter on a 1946 Packard Clipper Limousine
Posted by HH56 on 2020/10/5 10:05:11
The 46-7 uses a S-W magnetic type gauge which is fairly sensitive and does make rapid changes but is generally stable. I suspect either there is a poor or loose wire connection, poor ground to the tank or gauge unit, or more likely the sender has developed a condition where the wiper is not making a tight and stable connection to the resistance wire. Oxidation and corrosion on the ground paths to and in the sender or on the wiper or resistance wire is a known issue with senders. The phenolic support the resistance wire is wound around can also become warped or sometimes slightly deformed enough that the wire is not kept in tight contact with the wiper. Any of those issues will cause the gauge to flutter.
The Stewart-Warner sender used on the Clippers should have a resistance of 100 ohms empty and 0 ohms full. It is a project to remove the sender to test but as that is the usual cause of issues it may be the best option. You can see what the resistance is doing with an ohmmeter. When moving the float from empty to full and back the meter should have a smooth consistent resistance change throughout the full range (If the meter automatically changes ranges during the test it might jump a bit at the scale changes). If the meter jumps around or does not register a smooth change in resistance that slight difference in a magnetic gauge will be picked up and the fast action of the movement will cause the gauge to flutter or read erratically.
Here is quick rundown of the fuel gauge system and a basic test that can be done without removing the sender.Attach file
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