I’ve just recently got my g37 running again after it’s been sitting for 4 years. I put in a CJ fuel return system, 450 pump and 1300 injectors. I forgot to install the sending unit so obviously the gauge didn’t work. I found the sending unit, went to install it, and was missing the tiny plastic bracket to secure the float arm to the resistor of the sending unit. So my next step was to order a new sending unit off partsgeek. I installed the new sending unit and float, and the fuel gauge is still reading empty. I put it in diagnostic mode and the fuel gauge does go up to half. Maybe I connected the wires to the wrong pins? Does anybody have a pin out diagram from the pump housing side of which wires go where? I basically just found a YouTube video made by “Ah Duu” for fuel pump and sending unit replacement. However, his car is a G25. Not sure if that makes a difference for pin orientation though.. the fuel gauge worked perfectly fine last time I drove it. I thought for sure the new sending unit would fix the issue as that’s the only part of the fuel gauge system I’ve touched. Any pointers would be much appreciated.

 

Here is the schematic from a 2011 Sedan. I doubt there would be much difference, if any, in a year:


I would head over to NICOClub and download a copy of the factory manual for your specific car. You will specifically want sections MWI (Meter & Warning) and PG (Power/ Ground) for this issue (though I would download the whole manual as these links disappear from time to time).

Only thing I can think of is that the G25 might use different resistor values in calculating fuel level. Doubtful, but something to compare within the manuals. Or, your amp decided to kick the bucket- which is a known issue for these cars, however, the timing is off and I am not a fan of coincidences.