fuel gauge marking full with battery disconnected

[maltaspearo]

hi im new to this forum i have a 1991 4 runner in excelent condition for its age. today i noticed that with the ignition off the fuel gauge marked full.i found it strange that the fuel gauge was working with the ignition off . so i disconected the battery and the fuel gauge still marked full. i drove a 100 kms and the gauge went down a bit between 3/4 and full like expected. but the gauge was still marking with the ignition off and battery disconnected.what the hell is going on. it makes no sence to me
as far as i know the fuel gauge is electric right ????? or isnt it

can someone help me
regards john
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[laxbro19]

I just bought a '94 a couple weeks ago and noticed this too after I bought it. At first it freaked me out but after putting a full tank of gas in and seeing it move made me realize that's just how the gauge works. Not really sure why but hey, it's a 20 year old Japanese truck lol