My fuel gauge has never read above half, even when full. It sits at half until the tank is actually half full, and then it drops down like normal. This morning I have earthed the sender on the rear of the fuel gauge and it does go to full. So looks to me like the gauge is ok. Does this only leave the fuel tank sensor at fault?
Sounds like your tank sender has worn wiring on the resistance wires from full to half, mine packed up, I purchased a new one which lasted a month before going mental, now 3/4 is full and in the red is 1/4 so I play fuel gauge roulette a lot.
I've read a LOT of posts about the new fuel senders being rubbish, and not lasting that long. Is it labour / cost intensive to replace? Is it almost worth putting up with how it is? As long as it can accurately read when it's running low, that's all I care about!
I got mine from cool air and if I recall it was on sale but still about £30-40? It's easy to replace if someone has cut an access hole in the floor above the tank, if not it's engine out. I just fill up and do about 160 miles then refill, it's cheaper.
Theres just recently been a big thread on here about this, it was very informative, I would da a search.
