The Stovebolt Site Forums The Shop Area The Electrical Bay runtz question

Ok, my truck came converted to 12 volt but it was done in a haphazard way. Nowhere did I see the runtz resistor for the gas gauge. When I turn on the ignition the needle shoots to full and stays there eventhough I know the tank isn't.

So, I got a runtz but wasn't exactly sure which of the two wires that go into the gas gauge to hook it up to. I am assuming it would have to go onto the hot lead but it could also go on the wire that comes out of the harness and looks like it might be the sending wire.

Well, I tried it on both and the needles still shoots to full.

First of all, which wire does it go on. Secondly what is the problem that makes it show full? It looks like the tank might have been replaced by the PO.

The voltage drop should go between the hot lead and the gage. 12 volts may have damaged the gage or sender or both. I built a 6 volt regulator using an IC chip and transistor. It holds a constant 6.8 volts to the gage. A runtz is a resistor, it varys in voltage drop according to the load placed across it. In most cases this does not hurt anything. But I'm not sure how accurate your gas gage would read with one. You might also try checking your ground.

Are you sure that the sending unit is still working? When I pulled mine out of the tank I had 2 problems. One the float was gone! Secondly the float are was stuck and would not move.

Ok...as the father of the Runtz here is how the wiring goes....The Runtz goes between the hot wire of the gauge and the gauge itself. Remove the hot wire and connect it to the stud end of the Runtz. The end with the hole goes over the stud on the gauge, and the black wire is the ground. Besides being a solid state guage regulator , which is more accurate than the ceramic gizmos....the Runtz have some built in circuit protection so in the event something in your electrical system runs amock the Runtz will act like a fuse and protect your gauges from a sudden and painful death !!

As for your guage reading I would bet all of next weeks glazed donuts that you have a 12 volt replacement sender in your gas tank. While 6 volt senders work on 0-30 0hms 12 volt senders work from 30-90 ohms. That is why everything is reading full all of the time...the bottom of the 12 volt scale is the top of the 6 volt scale.

By the way your Runtz should have come with a page of instructions and a trouble shooting guide. If you want send me your fax or mailing address and I will drop some in the mail to you.....Thanks Randy

Hello Tony,
A voice from the past here. The most important part here is making sure the runtz has a really good ground. Sorry I've not been on stovebolt for a few months. Been busy remodeling my house, etc. My chevy has been doing just well sitting in the driveway, basking in the sunlight. This next year, new chrome and paintjob....
Craig

Oh, and one last thing...a Runtz is a SOLID STATE gauge regulator which means the out does not vary with the electrical load. A Runtz is able to accept a range of incoming voltage 8-20 to be exact whike still providing a constant 7.65 volt output. I build them that way because not every charging system is the same and there are a few with frayed wires and flackey insulation and unreliable voltage regulators...etc. In addition a Runtz has built-in circuit protection so in th event of a short in the wiring harness and everything goes crazy, the Runtz will act like a fuse to stop the flow of current to protect the dash gauges the most expensieve part of the equation.

I just want you all to realize the difference between a Runtz and a resistor o r the ceramic voltage drops. After 20 years in the barrel I knew a Runtz had to be more than a simple voltage regulator. I have worked on way to many sparkling wiring harnesses, the kind where all of the smoke leaks out. And most of you know by now how much it costs to replace your dash gauges. So a Runtz is cheap insurance. Now I feel better...thanks Randy

Randy, I have a question about the runtz. I run one in my truck and just today I had to jump start my truck after which I noticed that my gas gauge was not working. My question is, could jump starting with the help of another battery burn out the runtz. thanks. Frank

Wow I missed some of these replies. They will help.

This might be likely as it seems the tank and sending unit look new. If it is, can I do something about it? Or do I need the change the sending unit to a 6v?

Thanks.

Tony, wish I could help, I have the exact opposite problem. mine stays empty all the time, I replaced the sending unit, did no good, I have not checked out my guage as I Have a neck problem, so I have lived with it,I have only ran out of gas 3 times in 5 yrs. one time with my wife in my 52 , hot Tx july day,,boy, was she unhappy with me, has not ridden with me since, ...Fred

To work on my gauges I took my car cover (yes my truck has a cover) and wadded it up in the foot area of the truck all the way up against the firewall. Then I would lay out all my tools, hook up a light and lay down on my back and try to get as comfortable as possible looking up at the dash. If you have to hold your neck up at all you won't last two minutes. Make a pillow area.

In your case I hear you need to check all your grounds. If it is the gauge, I got a temp gauge from Mothertrucker and it works great and matches the rest in age/looks. I am sure he could pull a fuel gauge as well.

It really ought to take only an hour or so to change the gauge.

Tony, thanks for the suggestion about the pad...
Fred