99 Grand AM Gas Reading problem

I just got back from a road trip that was 115 miles out of town, well when I was coming back home, my gas gauge told me that it only took me an 1/8 of a tank to get home. I was like there's no way that I could get that kind of gas mileage on my car. So my question for everyone is what could possibly be wrong with my gas reading that I am getting. Normally I get 225 Miles on a tank of gas. While this is going on I have to keep filling up my car every other day to make sure that I dont run out of gas. Any suggestions?

When you fill up the tank, does the gauge go all the way to full? Does it ever drop below where it was when you got home from the trip after driving several miles?

My 99 also has problems with the gas guage reading. If I fill it right up it will sit on full (past full) for almost 200 km then all of a sudden it will drop to just below the 3/4 mark.

I think the wiring is going. I can be sitting idle at a stop light and my low fuel light will come on and ding even though the car is over half full. It will then go from empty to full and repeat this ordeal until it finally sits on 1/2 and then decreases how it should.

I always top up my tank every 2 days to ensure I don't run out too. It sucks not knowing for sure how much fuel is in the tank.

The gas gauge on my '93 Grand AM SE has never worked properly. It similarly reads 'full' for about 120 miles then drops rapidly.
Still, it's easy to figure out how much gas is in the tank. I know that my tank holds 13.5 gallons. I reset my trip odometer every time I fill the tank. I divide the number of miles traveled by the amount I fill up to get my mileage. After driving the car for a while I had a good idea of what mileage to expect, so I can make a good estimate for how far I can travel on my 13.5 gallons.

I have the unfortunate luck of owning a 99 Grand Am SE V6 and have had a similar problem. There were times when I would leave the gas station with a full tank of gas and then the low gas light would come on and my guage would drop to empty. It would be like this for about a minute and then my guage would slowly move back to full and the light would go off. I took it in to the dealer and they replaced the fuel module in the tank. Parts and labor ran about $600, but fortunately the warranty covered that.

225 miles on a tank of gas seems low to me. I usually get around 300 miles a tank on mine. Some things I would check are the plugs & wires, fuel filter and possibly having the injectors cleaned.

my 96 se is exactly like scaviola's 93. It will read full for 150 to almost 200 miles, and then drop rapidly for the next 100 miles i get. So i just set my trip each time i get gas and thats how i tell how much gas i have. I figure 300 miles to a tank is usual, so yea.