The Stovebolt Site Forums The Shop Area The Electrical Bay gas Gage resister, where on the key switch does it get conected to

I evidently hooked it up wrong as it always said Full. ram]n out of gas yesterday, and still said full. which screw on the key switch should I hook up the resistor to ? Thanks Paul

Paul,

If you're using a resistor to drop 12 volts to 6 that may not even be necessary. When I ran my now-restored '36 Chevy PU as a "rat rod" with a 12 volt system and the original 6 volt gauges back in the 1960s a knowledgeable old hand told me the 6 volt gauges would work fine on 12 volts. In about 5 years and 50,000 miles of trouble free use as a daily driver that proved to be correct. Now it's restored and back to 6 volts with the same gauges.

Isn’t there a sticky on fuel gauges, senders and 6 or 12 volt issues? It seems that they are an ongoing problem!

I know that it's wired wrong, just what terminal go's to gas sending unit. 12 volt is DEF wrong, got to step it down, have the restorer on wrong screw.

If you are dropping the voltage, you put the "voltage reducer" in series/inline on the hot wire that goes to the gauge. The one that is only hot when key is on.
Just because your gauge reads wrong does not necessarily mean you have it wired wrong. It could be a few other things.

WHAT TERMINAL: It should have an S for sender and a + for hot. Or it may have a red tag (or what's left of a red tag,) which is the sender terminal. If all else fails, the sender terminal is usually on the FULL side of gauge.

Search the forum for "runtz" to learn how to wire the gas gauge up. Make sure your grounds are good. Don't know about a 1936 system, but 12 volts will destroy a 1954 gauge.

"Make sure your grounds are good." - YES

A pegged gauge means a bad/open ground.

Run a small wire from a screw on the sender-to-gas tank to a good ground (frame, preferably).

"Don't know about a 1936 system, but 12 volts will destroy a 1954 gauge."

Gord,

Do you know of a case where that happened? I assumed my '36 would need the voltage reduced until how the gauge works was explained to me. I was told that the needle is pulled by 2 opposing electromagnets and increasing the voltage from 6 to 12 made both electromagnets pull twice as hard at any given sender float position so the actual reading was unaffected.

No offense intended, just curious.

Gord,

We have seen people post two stories, more often the sad story.

1. Put in a Runtz reducer and there will be no problem using 12v with a 6v gauge
2. Some (a few) people have posted that the run 12v with no problems with a 6v gauge.

I am not a gambler - I used a Runtz reducer.

Ray, my gauge was destroyed when the truck was converted to 12 volts. The wires used in the coil winding are really delicate. Perhaps in other years, they used heavier wires? It's no fun replacing the gauge, so, like Tim, I recommend a runtz.

If you want to roach a gas gauge quick like, put the hot lead on the wrong post. 12 volts probably will roach it faster than six volts.
I have 3 ADs on 12 volts with original gauges and 30 OHM sending units. They all work just fine. I thought that I had a problem with the first one that I converted to 12 volts and put in a Runtz and it did not do a thing. The problem turned out to be a combination of the float arm bent at the wrong angle making it hit the side of the tank and not bent right to go deep enough into the tank.
Bent it twice and work fine, last long time.
Carl

I've had my gas gauge running with a runtz resistor for a few years now, when I did the 12v conversion, with no hiccups. Could not imagine running it without Mr. Runtz.

Maybe I should put the Runtz back on my perfectly operating gas gauge which is fed 12 volts to see if it alters the reading. I think that I will wait until I have another reason to climb under that contortionist's nightmare before I do.

I know your post is “tongue in check”, Carl

Of course, leave well enough, alone.

You are not the only member who has reported no problem changing from 6v to 12v.

However, if someone chooses to use no reducer, and they fry their gauge, who will pay for the damage?

Mucho agree-o. Why take a chance? Unless you have extra temp gauges lying about. Besides with a runtz reducer costing less than $20

"Ray, my gauge was destroyed when the truck was converted to 12 volts. The wires used in the coil winding are really delicate. Perhaps in other years, they used heavier wires? It's no fun replacing the gauge, so, like Tim, I recommend a runtz."

Thanks for that information Gord. The '36 gauge probably has some really robust wire.

Tim,
I was actually being serious, although I can understand your assumption that I was not (I do have a pesky habit on disingenuousness from time to time).
I WOULD like to know if the gauge reads any differently with the Runtz installed.
Carl

Maybe the people who “burned out” their gauges mistakenly connected the 12v to the wrong post?

If I come to the Homecoming gathering in Lexington, I’ll bring a spare 1954 6v gauge and we can do a few 6v and 12v tests?