Technical SW fuel tank sender question

So I have a 56 Stewart Warner big logo fuel gauge. 6volt gauge with a voltage reducer running so I can run it on my 12 volt system.
With a standard SW 240-33 sender the gauge reads 1/2 full when the tank is full.
Multimeter reads 35 ohms across the terminals when tank is full and gauge reads 1/2
With a jumper wire across the terminals the gauge pegs at full.

No idea what these old gauges need for a sender. Or ideas of how to fix.

 

Look up on here on how to make a gauge tester. I have an older one I got off eBay, you can dial in until it reaches full and empty and check with a meter to find out what the ohms are.

 

I have one. It doesn't seem to work.

 

Yup, here is the thread.

https://www.jalopyjournal.com/forum...-will-work-with-my-dumb-gauge-thingie.862020/

Easy to make and super helpful. I've used it to test gauge function many times after making it.

 

I wonder if I can use a Chevy sender that is 0-90 and reverse the wiring on the back of the gauge?

 

I don't think reversing the wiring on the gauge is going to do what you want....

I wonder if a Ford sender 73-10 ohm might work? but it would be really helpful to know what the gauge wants.

Tell us more about the gauge tester, and what it does when it's not working right.

I have a bunch of resistors, I try them out and see what resistance it takes to make the gauge read at different levels. And play with the sender, while it's out of the car, and connected to an Ohm meter, to see what it's actually doing.

 

ignore ink marks those are from old jobs I am thinking ford /dodge is 70 empty 0 ohms full backwards of gm & stewart warners. sounds like you have a guage for a ford sender.ford ran 6 v gauges up into the 80's I believe a stock ford sender may be what you need

 

Make sure your float and its travel are correct for your tank height .

 

Or you could use one of these with the sender and gauge you have got.