I have a 54 Chevy 3100 P/U. The original gas gauge was not working. I suspect the previous owner burned it up when they converted to 12v. I can put a volt meter on the lead wire and it reads 12v to ground. I purchased a new 12v gauge. When I installed it, the needle on the gauge swings past full and buries the needs almost 180 degrees opposite the half tank mark. If referencing a clock, the gauge should read between about 10 o'clock for empty and about 2 o'clock for full. My needle goes to about 5 o'clock, way off the scale. Nothing changes when I disconnect the sending unit. The needle does swing back when I disconnect the lead to the gauge. Do I have a bad (new) gauge, do I have a bad (miss-matched sending unit, should be 0-30 ohms unit) or could I possibly have the two wires on the gauge reversed?
My car has 100000 miles.
My car has a manual transmission.
You would need to see if the sending unit is shorted to ground. If you test it with an ohm meter you should get somewhere between the 5 and 30 ohms. If you are getting 5, then the gauge will be at full; and if you get 30, it should be at empty. If you are reading too low on ohms, then you have a shorted sender. If you’d like some help looking at this, a technician from YourMechanic can come to your car’s location to inspect your electrical system in person and let you know how to best proceed.
Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing