I'm a newbie at wiring. Am wiring fuel guage on '49 GMC pickup, original gauge. There is a ballast resistor cutting voltage to coil. I ran power line off of coil to post on gauge with added Runtz reducer. I ran a new ground from gauge to back of cab with screw attachment. Ran new sender wire to post of gauge. I have 4.29 volts at one end of Runtz, 2.15 at post on gauge. Gauge reads empty when switch is on, doesn't move at all. I don't know which post is for power and which for sender, so I reversed the gauge post connections with the above setup and got reading of 1/4 tank (tank is nearly full). Needle moves when ignition switch is turned on. How do I determine which post is correct for power, sender? Is my ground correct? Is the gauge defective? The sender?
I have a 12v system but an inline ballast reducer gives 4.29 volts at the coil, from which my power line runs to the gauge. If the voltage at the gauge is only 2.15v, is that enough for the gauge?
Last edited by geraldine; 03/24/2013 3:55 PM.
