Fuel gauge only going to 3/4 when grounded?

So, got a couple things figured out today. Swapped in a spare IVR, now all 3 gauges go full tilt when grounded. Fuel tank sender shows 43 ohms, but I don't know how much gas is in it, so I'm not sure if that's accurate. Also, with everything hooked back up, the gauge shows about 1/8 tank. I'll fill it up tomorrow, see what it says then. And the oil psi gauge going full when disconnected? The warning lamp (for a dash without a gauge) was in there, back feeding 12v to the signal side.