Classic Winnebagos & Vintage RVs

So I had dropped the gas tank to clean it out and put a new sending unit in as the fuel gauge never worked.  I had gotten a NOS unit off of ebay for $40. The part number showed it to be for a slightly bigger tank. Before I put the tank back in and even before I installed the sending unit, I tried it out to see how the gauge registered. At "full" in the tank, it was showing only half a tank on the gauge.  I figured it was a poor ground and being in a rush, I put the tank back in. 

Well, the ground was fine. I checked the wiring, which was fine. For some reason, it was showing about 130 ohms at 1/8 tank, instead of  somewhere around 60 ohms. (Dodge senders are 70-10 ohms.)  If the ohms were low, it would be an easy matter to just add a resistor inline. But it was high! So I did some research:

Basically, you put a resistor in parallel with the sender. This reduces the resistance.  So after a little trial and error (their formula didn't seem to work for me) I put 66 ohms in parallel, and it is showing the correct 1/8 tank.

My question is: will this remain reasonably accurate at other fill levels? I know it's accurate at 1/8 tank which I guess is the most important. :-)


brian

Dodge senders are 70-10 ohms

Quote from: DaveVA78Chieftain on May 19, 2022, 10:03 AM
Dodge senders are 70-10 ohms

is 70 full or empty?

10 ohms full
70 ohms empty