How much useable fuel (TEST) is in our 2.5 gen 38 gallon gas tanks

(This is a repast from the 2.5 gen forum page. Thought more people might see it this way and maybe it could answer some questions?)

Hi everyone with a 2.5 generation Tundra with a 38 gallon tank. My truck is a 2021 I just bought with 22,500 miles on it. My question was why hasn't anyone run one of these tanks dry? The answer is that it takes time and could be problematic depending where the pump goes dry.

I took the challenge and here are the results!

When the low fuel light went on I set my trip odometer to 0 miles. When I was near Costco I filled my empty 5 gallon gas can with a measured 5 gallons of gas. I also put my trusty syphone hose in to make the transfer quick and easy once I ran out.

The first 40 miles I drove around town getting about 11 miles to the gallon average. Today I decided it was taking too long so decided to expedite the project. With all of you reporting that it takes 30 +- gallons to fill at low fuel warning, I figured I should be able to go about 100 miles past the low fuel light getting about 12.5 mpg. to suck that tank dry. I live in Lodi CA and this area is flat farm land. I didn't want to be on a narrow or high traffic road so I stuck to the valley roads through the cherry, pear, almond, walnut and other crops cruising along at 50 - 55 with stop signs every few miles. I drove up past Walnut Grove almost to Sacramento and back all on those minor low traffic roads.

I was wondering if this thing was ever going to run out when it stopped with out warning, shortly after making a left turn on to another road from a stop sign. It didn't so much as hiccup just stopped running. I didn't try to restart I just pulled over and wrote down my mileage, reset the trip odometer and put in the 5 gallons.

I cranked it and it started as though nothing had ever happened. I drove straight to Costco 5.5 miles away and filled it up - - - Drum Roll - - - the filler clicked off at 33.2 I then waited 30 seconds and pumped until it stopped again, totaling out at 33.5 gallons of fuel. Plus the 5 gallons I had just put in it minus the 5.5 miles at 11 +- miles per gallon traveled from the addition of the 5 gallons. It ends up that I put 38 gallons of gas in that tank! I had traveled 107 miles from when the low fuel warning light came on. It seems fairly safe to assume you have 8 gallons useable left in the tank when the low fuel light comes on. Depending on your fuel use average will determine how far you will then travel before the engine stops.

Now I will let you all figure out what happens when climbing up a grade or worse yet once you top the grade and start down the other side with an almost empty fuel tank. I believe it will use up the gas in the tank when traveling on level ground. I believe I have proved that my truck will at least do that but I don't know about yours.

In April took my 2.0 generation 2010 Tundra with a 26.? gallon tank, towing a 25' travel trailer on a 10 western state trip and I had that same gas can full of gas in the back all wrapped up in a black plastic garbage bag so it wouldn't be noticed. I traveled 6,000 miles and didn't ever use that gas, however I did have it there as security. At one gas stop I put in 25.5 gallons of gas!

When I take this truck to Alaska next summer towing my little trailer, I'll have that same gas can in back! Yes, I am happy with my 38 gallon tank. After all it's only money that it takes to fill it right? You all that live outside California have cheap gas, at least that's what they say.

There's my experience for what it is worth. My next challenge is find out where the pump is located in the tank and what type of well or plastic baffles surround the intake sock. With that knowledge other assumptions might be made?

ShopMan2

 

Welcome from LA (Lower Alabama)! Thanks for your tenacity! I wouldn't make a habit out of it because as your truck ages it will accumulate debris in the bottom of the tank that will plug the fuel pump eventually. But it's good to know the results from your experiment!

 

Welcome from NY.

 

Welcome from OKC! Not a good idea to run it low or overfill it. Doing both can cause problems that would be best to avoid. Good luck!