Gas tank problem

I have a 2005 Jeep Liberty that I just recently purchased. I was letting the gas tank get down to two gallons so the warning light would come on. Wanted to check to make sure it was working and see how accurate it was. Guage was reading a little less than 1/8 of a tank when the engine started to spit and sputter and hesitate. Didn’t know what was going on other than the gas was starting to get a little low. So I headed to the station and filled it. It took 17.5 gallons to fill and it has a 20.5 gallon tank. After I filled it, everything was back to normal. What would cause this to happen when there was still 3 gallons of gas left? I checked with the local Jeep dealer and they said they never heard of a problem like that.

Copied and pasted from the 2005 Saturn View Gas Tank Capacity thread:

…just because the rated liquid capacity of the tank is 20.5, that doesn’t necessarily mean all of that is usable-- you have to figure that by the time you’re at your last gallon or so if the gas is sloshing around, it can slosh away from the fuel pickup. Also, the fuel pump, gas gauge sender, and the various other parts that are in your gas tank these days also take up some tank volume.

That doesn’t make any sense. I could see if it got down to a gallon or less but not with 3 gallons left. There’s no way the parts that are in the tank take up 3 gallons worth of space. We currently have 1 other car and have had 2 others in the past several years that all have had the 2 gallon warning light and none of them have ever acted like this one does. I could always get them down to the warning light coming on and then driving another 10 to 20 miles with no problems at all.

Oh, right. Sorry, I mis-interpreted your post. I think there’s two issues going on here, one being that the usable capacity of your gas tank is less than the listed liquid capacity, which is pretty much normal. I think the other issue is that the gas light isn’t working.

So first off, does the light come on when you first turn the key to run?

Yes the light comes on

It could be that you have a weak fuel pump and it is no longer up to pumping from a nearly empty tank.

Gas gages are not designed to be as accurate as you’re assuming. You really have no way of knowing how much gas is left to the accuracy you think.

You should also know that your gas pump is cooled by the gas pumping through it, and doing what you’re doing could end up with a fried pump. I recommend against the practice.

I would NEVER rely on the warning light. When the gauge reads 1/4 tank or less, it’s time for gas. As Mountainbike said, running the tank lower than that risks overheating the fuel pump.

Gas gauges are just not that accurate, and neither are the warning lights. Where did you read the “two gallons?” Are you sure it doesn’t say APPROXIMATELY two gallons?