What did you change? Is it an aftermarket sender? Should work fine.

 

 

Not familiar if replaced with aftermarket kit. The original used a Constant Voltage Regulator usually attached to the back of the instrument cluster that monitors voltage fluctuations from between 0-10 volts to the instrument gauges. Usually can tell if the CVR is faulty if the other gauges are also acting up. If aftermarket possibly similar item in kit?

Not sure "unbaffled tank" if have not done so, suggest check the sending unit float replacements run around $5. Also check the fuel gauge circuit.

If of the plastic CC type cluster then may find attaching a ground strap from metal portion of cluster to ground will help?

Anyhow, food for thought??

 

Well what kind of gauge is it? Let's not play 50 questions here I'm trying to help you lol. The OEM type gauge, is fed by chopped DC of the voltage regulator, is slow as molasses to respond. Now keep in mind if the float has a pinhole and filled with fuel it will behave as you describe.

 

Tedster is right. The sender and gauge have to be a matched pair so they play the same game. The original sender is about 73 ohms full and 13 ohms empty and about 5 volts. If the gauge you have is playing by a different set of rules, it ain't going to work.