Gas gauge problems

Dana67Dart said
First do as others have said and measure the resistance that the sender is providing to ground.

This chart is from my aftermarket sender vs my NOS sender.

yours should have similar readings at a particular gallons in the tank.

you can see on the chart that the NOS mopar sender is not linear but the aftermarket on is.

Non linear matches OE gauge Linear gives bad readings on OE gauge

View attachment 1715213080 View attachment 1715213081

Curious,... How do the bends on the float arm and the position of the sweeper box compare between the OE and the aftermarket? I'm wondering if there is a slight difference in the float location on the arm, relative to the sender body and pickup tube, and if that has something to do with the difference in the profiles as you fill it.

I'm thinking if the float is pointed down more at the bottom of the stroke, it is going to move the arm more at the bottom than the aftermarket one if the float arm has a lesser angle. Once you get some fuel in there, and the arm starts to get at an angle, it would move less for a given rise in fuel. Don't know if I am explaining what I am thinking correctly.

Reason I say that is the OE reacts once 2 gallons have been added, while the aftermarket doesn't react until 4 gallons have been added. That tells me the OE float sits lower in the tank. If the windings in the sweeper spring are consistent, it should be linear, but it isn't. That's why I'm wondering if the bends in the float arm are different, causing it to move different amounts as the fuel level rises.

Just a thought,... sorry,... didn't mean to get side tracked.