The Stovebolt Site Forums The Shop Area The Electrical Bay Gas gauge 6v to 12v

Dave it sounds to me like an issue with the sending unit and that can be fixed. Please remember a couple of things. 1...your sender is a resistance affair. When the float is all the way up (tank full), the sender must register 30 ohms. 30 ohms of resistance to ground to be specific. And when the float is all the way down (tank empty) sender must register 0 ohms (another way of saying no resistance at all or straight to ground). 2...your fuel gauge cares more about current than voltage, but since you've already bought a 12 volt gauge, let me concentrate on that for the time being. That new gauge...was it specifically made for the AD truck or was it an add-on generic type gauge? And that new sender...was it a 0 to 30 ohm sender or could it have been a 0 to 90 ohm sender? GM changed to 90 ohm tank sending units in 1965 and those won't work on the AD gauges. Almost all of the add-on gauges you buy will be 0 to 90 ohms and then when you wander way off into the weeds, Ford and others used some different ohm ratings. The AD gauges look for 30 ohms of resistance to display F on the gauge. More resistance will cause them to read over-full. Let's start there. Do you own a handheld electrical tester? If so, unhook the wire at the top of your sender with a full tank, set the handheld tester to the ohm reading setting (will look like a little horseshoe) and set the selector as low as possible (could be 200 ohms or 400 ohms...something like that). Then connect one lead to the connection on the top of the sender and one lead to ground. That will get us started...