Gas Gauge / Sender Problems

[taclem]

Can anyone tell me if I can install a resistor in line with my sender fuel gauge? I have stock 66 gauge and the tank has a 73 sender in it, what can be done to make these compatable. The gauge shows full until it is empty then just starts to move.
Thanks, Taclem

[65Guy]

From what i under stand that 66 and older used a 30ohm sending unit and 67 and newer used a 60 or 90 ohm sending unit, but as to the question can you use a resistor im not sure i was told it wouldnt work but dont hold me to it.

[TR65]

You can shift the center around with a resistor but you can't change the range. My advice is to change the sender.
TR

[nomrlz]

i believe they make convertors. i'm putting a 99 Z28 tank in the boys 66 and he wants to keep the stock gauges. i was told to get a convertor kit for it

[BMSJaX]

No adding a resistor will only increase the ohm range. you could make a 0 ohm - 30 ohm sender into a 60 ohm - 90 ohm, but you cant go backwards by adding more ohms

[raycow]

Yes, you can mickey-mouse it to get the full range, but it will be non-linear. Get a resistor that is close to 45 ohms (47 ohms is a common value) and connect it in parallel with the tank unit. That is, one side of the resistor goes to the sender terminal of the dash gauge and the other side goes to ground. This will effectively give you 30 ohms on a full tank and 0 ohms on empty, but as I said, it won't be linear. For example, when the tank is actually half full the gauge will show 3/4 and when it is 1/4 full it will show 1/2. When you are down to 1/10 full the gauge will show 1/4, so you get the idea.

This is cheap and easy to do, but I would consider it to be a temporary fix only, until you can get the correct sender.

Ray

[kauaiman]

I read an article on another site that say buy a potentiometer from radio shack for 2dollars and put it in parallel with the sender wire. I'm going to try it on my 1963. You fill the tank then move the potentiometer to make the gauge read full.

[TR65]

Raycow is right.

I plotted it out. So the tank will seem full for a long time and get empty quick.

TR

[raycow]

TR65, that is really neat! Thank you very much.

Ray

[lakeroadster]

TR65 to the rescue. The old adage "A Picture is Worth a Thousand Words" (or in this case a graph).

Thanks for taking the time and effort to do this.

[taclem]

Wow, Thanks guys this is the info that I need. Every time I ask a question, I get the answers that I need.
Tom

[irish1966]

So, if I am understanding this correctly, if I switch to a 0/90 gauge in my truck, I then need to change the sender to a newer sender, right?

[TR65]

Irish,

I think that the 0-30 ohm sender going to a 0-90 ohm gage would register about 1/3 tank when full and go down from there. I don't see a way to make it better than that. Maybe Raycow will weigh in with another idea.

I think the best bet is a new sender.

TR

By the way, I have been running the fix shown in my post above for some months now and it works pretty good. You just have to remember that when it says 1/2 tank it is really just 1/4.

TR

[irish1966]

thx man