I'm having problems with my fuel level gauge. I have Autometer Phantom gauges in an FFR MKI. Gas tank is from a 91 Mustang. The gas gauge was reading backward, so I measured the resistance of the sending unit. It shows that it is about 35 ohms when full and just under 200 ohms when empty. So, I swapped gauges with one that reads 33 ohms when full and 240 when empty (I know, it's not an exact match, but it was the closest thing I could find). Now the gauge reads in the correct direction, but only reads 3/4 full when the tank is full. I haven't had the chance to see what it reads as the tank is emptied, yet. So, I'm wondering if there could be something wrong with the sending unit itself. I didn't build the car myself, so I'm not exactly sure what sending unit is in it. I pulled the unit a few days ago and snapped a couple of pictures.
Can anyone tell me if this is the stock Mustang sending unit? Or, if not, what this unit is and how I get my gauge to read correctly?
Thanks,
Darren