It's been a while since I posted here but my car is at around 110k miles, it's an 05 G35X sedan. I recently had faulty gas readings on the fuel gauge so I decided to replace both the driver and passenger side fuel sending units including the fuel pump. Unfortunately, I am still getting an inaccurate reading on my fuel gauge. It seems like no matter what my fuel level is at the line will always read 3/4th a tank left. However, when I refill the tank with any amount of gas, it will read full and go way past the full line. I took it to my mechanic and he even took out the fuel sending units and inspected the wiring on it and reinstalled it. Does anybody know what is going on here? Is there a way to recalibrate the fuel sending units? Is it the cluster? Thanks guys

in some situations I have seen where the actual cluster is the problem and not the sending units so it is a possibility it was the cluster all along

There is a self-test you can do for the cluster. I forgot the exact procedure though.