Low Fuel Level Better Performance

I have a 2002 V6 Tacoma TRD. I have noticed for some time that the performance of the truck improves significantly when the fuel level goes down to 1/4 of a tank of fuel or lower. I have asked others to test this out and my brother confirmed that I was not imagining this.

Does anyone have any ideas on what might be causing this? Has anyone else experienced this?

 

How was this confirmed? Dyno?

 

define performance.

Off the top of my head, that is a significant amount of weight missing when you're low on fuel. I think it weighs 8 or 9 pounds per gallon.

 

A gallon of gas is just over 6 pounds IIRC so a full tank would weigh about 108 pounds, not enough to make a significant difference or even a noticeable difference in performance which has yet to be defined by OP and remember its not good to run your fuel low especially for performance because that is how the pump stays cool

 

Sounds about right. I thought the pump was cooled by the gasoline moving through it, and not around it.

 

The performance difference and the operation of the engine is distinctly noticeable. Also weight can be factored out since I have driven it on a quarter tank with a load in the bed. The engine actually runs smoother.

Fuel pump?
Injectors?

 

It doesn't intuitively make sense that anything performance related would change. The engine simply runs as long as it gets enough fuel. The second that stops happening, the engine cuts out and dies.

Are you sure you're not just babying it or driving more carefully? My driving is nearly perfect when I"m running low on gas.

 

Maybe it's a weak fuel pump. Just keep it at 1/4 tank or less and you'll be OK.

 

I noticed it too. It must be weight. I feel like my last car did the same thing. Just didn't feel as snappy or a:mads quick at overtaking other vehicles right after filling up at the station. But when the empty light comes on it feels a bit quicker.

 

Sounds like simple physics to me.
Why the hell do you think drag cars only carry enough fuel to get a 1/4 mile?
Answer = Because its heavy.

 

No dude, neither.
Regardless of the full load in you truck as you say, just because you have less fuel in your truck does not magically give you more horse power. This is a placebo effect.

 

while it doesnt give you more horsepower, it makes the horse power you have more efficient. its easier to move around 3840 vs 3940 (just a #).

The 100lbs works out to be somewhere around 1hp. those guys in racing forums are always looking to shave weight by removing things like the passengers seats and carpeting. a general rule is if you can get 100lbs lighter you will gain around 1hp. some say it will gain .1 in a quarter but im not sold on that one.

does that mean if he has 1hp more it will "seem" faster? prolly not. im leaning more towards a feeling of the truck's body roll and the lack of fluid moving thru the tank.
with a full tank the truck may sway and slosh a little more. if youre running around with a six pack in the tank, its not going to wave back and forth inside the tank like some sort of wave ride at the theme park. i think that would give the "feeling" of beign lighter and quicker. a full tank would be a heavier and fuller feeling. think of a full stomach after a thanksgiving meal and a long day with out much to eat at all. you will feel lighter and it will seem easier to get your fat ass going. jmo

 

lol, I say we all just go for a 5 gallon gas tank, then we would be set!!