Wow, they are probably blaming it on towing something too heavy and don't want anything to do with it, though I doubt you did.
The fuel gauge thing is caused by the shape of the tank rather then the sender. Though Nissan has had cases of bad senders on other models. I can drive 60miles and not have a light go out then it drops quickly to about 3/4 and is pretty consistent to about 1/3 haven't really run it lower then that often enough to know the last 1/3. THe tanks in the Z are shaped like an upside down U so there's a lot of fuel in the top end compared with the rest. Other cars are the opposite they drop quickly but take forever to get to E.
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