Guest REX STALLION Posted February 11, 2011 Share Posted February 11, 2011 My fuel gauge is not working and I am pulling out my gas tank to do some trunk repairs so I thought it would be a good time to test the sending unit. How does one go about testing said beastie? this is in my `64 . Link to comment Share on other sites More sharing options...
JZRIV Posted February 12, 2011 Share Posted February 12, 2011 The sending unit is a variable rheostat. Connect an ohmeter to the lead wire and the other to ground (any part of the metal sending unit framework).Pretty sure when the tank is full you should have the most resistance. As the float drops the resistance should go down. This simple test will at least indicate if the sending unit is providing a variable signal and indicate a very good (but not 100%) likelyhood the sending unit is OK. I'm not sure exactly what the actual min and max ohm readings should be. Link to comment Share on other sites More sharing options...
RivNut Posted February 12, 2011 Share Posted February 12, 2011 (edited) From what I've read, the 63 and 64 units are a 45 ohm unit and the 65 is a 90 ohm unit. You'll get into lots of arguments with the guys who make aftermarket gauges; they claim all GM products went to 90 ohms in '64.You may also discover that your sending unit is coated with a build up of lacquer that keeps a signal from being sent to the gauge. This happens when the gauge sits for a loooooooooooooooooooong period of time with the same amount of gas in the tank and doesn't travel like it would on a daily driver to keep the lacquer from building up. You might just need to give it a good cleaning to get it working again. I know the gauge in my '64 goes to full then stops just a little over a 1/4 tank, even when the tank is empty. AAA will attest to that; they had to rescue me once.Ed Edited February 12, 2011 by RivNut spelling (see edit history) Link to comment Share on other sites More sharing options...
Guest Riviera_Rob Posted February 12, 2011 Share Posted February 12, 2011 I was just gonna say 90 ohms! Didn't know it would be 45.Anyway, I just picked up my first Riv a weeks weeks ago, filled her up once and I've been impressed by her gas mileage................... errrr, maybe not?? :-(I better get some gas!-Rob Link to comment Share on other sites More sharing options...
60FlatTop Posted February 13, 2011 Share Posted February 13, 2011 My '64 drops dead at 1/4 tank. I learned that before I had AAA. Actually, I got the AAA when I licensed my first Jaguar... with extended towing.GM made lousy fuel gauges. They probably figured if you could afford a Buick you could keep the tank full.I fill mine on Sunday. Of course I've only put 20,000 miles on it in 32 years.Bernie Link to comment Share on other sites More sharing options...
Guest rsteere Posted February 19, 2011 Share Posted February 19, 2011 Keep in mind the tank has to have a good ground for the gauge to work. A jumper wire with a couple of aligator clips or a jumper cable can be used for a quick test.Randy Link to comment Share on other sites More sharing options...
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