Original gas gauge in my 33 Dodge used a positive ground elec. system. I am using an updated negative ground system. Plus, the original wiring was six volt and is now 12 volt. A "Runtz" will not work to reduce 12 to 6 volt for an original pos. ground sender/gauge. Anybody made this conversion or do I need to change out the gas gauge?
Switch which wires? I switched the wires on the back of the gauge, no difference. It is a two post gauge. One for the sender wire from the tank and one for the ign. wire. In order to drop from 12 to 6 V, the ign. wire hooks to the Runtz which hooks to the ign. post. Directions for the Runtz state it can't be used on a positive ground wiring set up.
Chopped51, yes I did change over to a 12 volt negative ground system but the original gas gauge worked off a 6 volt positive ground system. I' trying to figure out if there is a way to use the original gas gauge.
i have a 38 plymouth and i have been running 12 volts on a 6 volt gauge since 1983 and it hasn't burned up yet.
the sender doesn't care if its 6v or 12v. it measures resistance in ohms. just put a voltage drop 12v to 6v on the power going to the gauge
If it's a normal resistance sensing gauge; just switch the ign wire (reduced to 6v) & sender wire on the back of the gauge.
Rich B, As mentioned in post 3, I did try switching the wires, using a runtz voltage reducer, on the back of the gauge. No, difference. Gauge needle immediately goes over to full.
I did read that, and was going to add more to my first post; but had to do something and never got back to it. Was going to say, hook up the power wire and just work with a ground wire on the sender stud. A test for most regular gauges, with power hooked up will be full scale one way with the sender wire un-hooked and full scale the other way with the stud grounded. If no luck; maybe pull the gauge out of the panel and see if it looks like a normal resistance gauge or something odd like Ford's King-Seely (sp) bi-metal strip gauge. If it looks normal, maybe a close inspection of the insulators where the studs p*** thru the mounting plate will show a fault. Found that to be a problem in the past. If you get the gauge working and find fault with the sender, I'm sure you know the sender has to match the gauge; there is (was) a thread on here somewhere on testing the resistance range on a gauge to learn what was the best match of currently available senders and how to "tune" it a bit with added resistors.
Called Tanks, where I bought the gas tank and sender, today. Was told switching to 12 volt didn't make any difference and that switching from a pos. ground to a neg. ground also didn't make any difference. It's hard for me to believe that. Tomorrow I will get out my ohm meter again and start tracing from the sender forward.
Found the problem----pinched Sender wire. Still haven't figured out why 12 or 6 volt and pos. or neg. ground makes no difference. But, I'm content. The gauge works.
I switched also (same as Fat47) using the original 6 volt gas gauge and it reads backwards. Will reversing the wires remedy this. I am afraid to try for fear of damaging the gauge.
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