[Trueoo7]

I have the Autometer gauges and they all were working fine until today. Ran out of gas, luckily at a friends house. He had a 5 gallon can of regular, so we poured it in and had to prime the pump but it started up. A little embarrasing to say the least. The gauge was reading in between 1/2 and 1/4 full. Went to fill it up and it only would take about 4.5 gallons more. (gauge still reads between 1/2 and 1/4 full) I thought these tanks held 14 total. I have the stainless steel type. When key is switched off the gauge comes all the way down to empty so its not stuck. Where do I go from here? Do I check the sending unit or the gauge. How hard is it to get to the sending unit, I guess I have to drop the tank. If its the gauge what do I test for?

Thanks
Trueoo7