My Ion does not give me an accurate gas reading. What could it be? on 2007 Saturn Ion

I filled up my tank last night no more than a mile from my house, did not go anywhere after that. When i turned on my car this morning it was missing almost a 1/4 of the tank. So i went back to fill it to the top again, and it only allowed me to put in $0.40. I noticed this a while back, especially when it gets below a 1/4 tank, it seems as the gas evaporates form the reader. I ran 7 days with my "LOW FUEL" sensor on. I think the floater or gas pump might be worn out, or even broken. How can i figure this out?

Asked by for the 2007 Saturn Ion
fuel sending unit
1 more answer
Your fuel level sending unit is acting up.