Fuel Guage Goes Up Then Partly Fades -- 72 Swinger

Dana67 -- That's interesting and I never thought of that. So you're saying that the original mechanicals (and maybe this allegedly electronic one) would surge with a full 12V for a few seconds and then start oscillating to drop down to 5V? Maybe some sort of sequence to get all the bi-metal in the IVR and gauge up to temperature? I don't recall my dart's gauge ever doing that, but to be honest I've been without a working gauge for over a decade -- so long that I might have just forgotten. (I do know that many new cars peg the gauges then settle back when you start the car -- maybe they're mimicking old Mopars hah!)

At any rate, you may be right, and my #1 test of my NOS Mopar guage will let me know if that is right. Results will be forthcoming if I can just get a few hours to test it this weekend.