Fuel Gauge Discrepancy

[STT22]

Wondering if anyone else has encountered a similar problem with their fuel gauge accuracy?

Here's what happened: After filling up my tank, the fuel gauge system showed a remaining range of over 330 miles, which seemed off compared to the usual estimate of >270 miles I get after a refill. Over a few days, while driving around 50-60 miles, the gauge strangely didn't show any decrease in fuel. Moreover, the estimated remaining range was inconsistent—initially indicating >330 miles, then suddenly dropping to >300 miles (after driving only a few miles) and then 290 miles.

Has anyone experienced anything similar?

 

[Top Cat]

So, Brown Davis tank fitted. It is a tight fit but went in okay. I took up Steve B's suggestion of a bigger fuel filter (VN Commodore) because its metal not plastic and is a lot bigger. Set it up against the right hand side of the tank nicely and a stone cover to go over it.- See photo of Steves attached
Filled it with fuel, topped up the main tank and packed for a 6 day bush trip through Mt Ive, Gawler Ranges and went over some rough station tracks. Checked the springs eg distance between tank frame and exhaust, recoil etc and all looked good. No evidence of touch.
2,300 later the Grenadier pulled in back home. I checked the tank again and no issues. Would recommend putting it in. However some of their instructions are a bit footloose and some things are left to you to sort out. Well worth the money!
Re fuel usage, on stone track tarmac dirt etc my average was 11.1l/100 on the instrument panel but when I looked at the stats for the trip on the Offroad menu it said 12.5l/100 when both were calibrated beforehand so not sure
My hand calc comes in around 11.5