Gas Gage Help!!!!!

Ok, here's the story, car was converted to 12 volt (54 Chevy) and no one put the reducer for the gage, burned up the sending unit. I replaced the sending unit and nothing. i bypassed the origional wire and nothing, pulled the unit out and grounded it and tried again nothing. the gage has power going to it, but with the ignition "on" should there be any power running outta the other side of the gage? could the gage be blown from accepting 12 volts? if i put power to the sending unit side the gage jumps to full, but when there is no power on the sending unit side it drops back to empty? is there any way of testing the gage? anyone in hamb land have any ideas, this is pissing me off.

 

I believe that you should see voltage coming out of the sending unit side of the gas gauge, the sending unit is a variable resister so the gage is basicly reading the resistance in the sending unit. Unfortunately it sounds like the gage is TOAST.

At least this is what I think.

 

The sending unit is just a reostat, and 12volts won't hurt it.
Sounds like the gauge is toast.
Ground the wire going to the sending unit. If the gauge is OK, it will go way past full.
If it doesn't move it's junk.

 

If i ground the sending unit, nothing happens, if i put 12 volts to it it pegs full, the sending unit is from national chevy association. wonder what happens if i pull the reducer out? might have to try it

 

Ths gauge measures current, it works by applying voltage to one side of the gauge, then through the gauge to the sender, which a variable resistor back to earth or negative, so depending how much gas you have in your tank sets how much resistance, therefore how much current through the gauge.As the gauge would not be able to handle the extra current ( because of the higher voltage ) your gauge is faulty. The sender unit should not be affected by the higher voltage. Hope I haven't confused you.