See what the others say. I don't think you can drive the fuel sender backwards through the IVR.
It looks to me like you can put 6 Volts + on Fuel gage I, with fuel gage S connected to a resistor or a spare fuel sender.
6 Volt negative connects to the other side of the resistor or the fuel sender body.
Was there capacitor on the IVR output stud or anywhere?
