Hey guys, posting here again. My G35 has that issue where the fuel gauge reads wrong, and i've been trying to fix it. I cleaned both of the sending units and no luck, then i read it could be the cluster gauge. I dont even want to touch it if theres a chance it wont fix the problem. My question is, is there any way for me to measure my fuel tank without using the cars own gauge? i see some gauges and devices on amazon and stuff, wanted to see if anyone else has tried something like that? i've been calculating my mileage but i feel like its inaccurate and i'd feel a lot safer if i had an actual gauge or something. i want to try something but i really dont want to waste money lol

Measure the resistance signal sent to the instrument cluster. If the signal is correct then the cluster can be replaced since you've proven that IT is the problem.