New GM style fuel pump/sender results in wonky fuel level readings. known issue?

[rjd2]

hi folks-I put a new GM style fuel pump/sender unit in my car when I restored it. i've always kinda tried to keep the car near enough the mid level, so it was never anything i paid a ton of attention to. I recently siphoned some ethanol fuel out of the tank to replace it with ethanol free, and i noticed that when the tank was bone dry, the fuel level read just below the half mark. no low fuel level light came on either. i filled the vehicle at a station, and the gauge reads full when full. is this a known issue? is there anything i can do to amend this? thanks if so!

[Bitsyncmaster]

Are you running a gauge ECU to use that sender? The original sender is 0 to 90 ohm so that worked with the gauge without an ECU. Most of the GM senders are 248 ohms full and 40 ohms empty.

[rjd2]

Are you running a gauge ECU to use that sender? The original sender is 0 to 90 ohm so that worked with the gauge without an ECU. Most of the GM senders are 248 ohms full and 40 ohms empty.

Aha! That would explain it. I do not have a gauge ECU. and 0-90ohms factory, new unit 40-248 ohms, would exactly square with what i see, as my current "midway point" is with the tank bone dry. Thanks! No to source a gauge ECU...