Smartcraft fuel quantity issue
 

On the way to breakfast the other day and the fuel readout began dropping quickly. I had recently filled the 60 gallon tank. In maybe 90 seconds it steadily dropped to 0 and triggered a LOW FUEL alert.
I stopped the boat thinking I had a massive fuel leak. I checked the bilge and nothing, not even the smell of gas. Cranked it back up and continued on. On the way back home I watched the gauge climb back up to 96% steadily.
Next time out it read 0 from the start and had not recovered.
From what I’ve read a fuel sender should have @ 240 ohms of resistance when empty and 33 when full, so an open circuit would result in a 0 reading. I also noticed the trim indication tends to “float” a bit after I release the trim switch where it used to be rock stable. The motor does not move after trimming, just the indication.
I’m wondering if a bad ground somewhere could cause both issues as they both began at the same time? I did check and clean both sets of battery terminals. Getting 12.3 volts engine off and 14.1 with it running. Voltage is steady.
Anybody had similar symptoms?