TURTLECON

Ok, so this might sound a bit dumb, but maybe someone can clear this up for me... I've got a 23 gal gas tank(verified by my build sheet) yet I've never filled up more than 18-19 gals when almost bone dry. What gives? Where are those 3-4 extra gallons?

-Mike

Jeek.OlllllllO

Hmm I have had the same problem and I have wondered the same thing maybe there is 3-4 gallons left in your tank I want to try to see how much I can put in my tank if I run out of gas but I need some gas cans lol

Freewill

Even when the trip computer has given up estimating miles-to-empty and the gas gauge is down past "Oh shit!", I can only get 15 gallons into the 18.5 gallon JK tank. This is actually a very good thing on a vehicle that can get so far into the back country.

Rob 12B1P

Maybe your skid plate is pushed up onto the tank?

Rule18

^^ I agree. It's also a marketing psychology thing. Manufacturers don't want their vehicles being seen on the side of the road. As you drive by a vehicle on the side of the road, you might think that vehicle is prone to failure (even if it was user error). They solve that problem by having the fuel gauge lie to you. It's easy for them to do since everything is computer controlled.

Sporticon

The most I have gotten into mine and I was sitting just below the empty mark was 19.8 gallons. Most manufactures have the gauges set at about a 2 gallon reserve once you drop below the E mark.

Jeek.OlllllllO

I am guilt of that!

AtlJeepsTer

Here's a Fun way to Hear why the Manufactures do this. Enjoy!!!

Back in the old days, we didn't have all these gadgets to tell us how full something was or how hot the day was, we just looked at the thing or noticed how much we were sweating. Now that we have all the fancy gauges and buttons modern life provides to us, we may have gotten a little bit overdependent on them.
As it turns out, many of these gadgets are scarily inaccurate or even deliberately configured to lie to and appease us.
For most people, there's no mystery to fuel gauges other than "Why is something spelled 'gauge' when it is pronounced 'gage'?" The gas tank is 100 percent full when the needle is pointing to "F" and completely empty when the needle is at the bottom, right?


Actually, no. You might have noticed that for the first 50 or so miles, the needle hardly moves down at all, whereas when you get down to the last bit of gas, the needle goes down to empty and scares the shit out of you, even though you find out after filling up that you still had well over a gallon left.
The biggest reason for this is the float used to measure your gas level, which is a bulb on an arm like the one in your toilet tank. Bulbs are always going to be fatter than the arm, so you can go from full (float is completely submerged) to a little less full (float is floating on surface of gas but is touching the top of the tank) without the arm moving.


For the exact opposite reason, you can go from almost empty to empty without the arm moving.



So since your fuel needle is going to be in the same place for both full and slightly less full, the engineers chose to point it to full. The alternative is a fuel gauge that would never point to full and just confuses the driver. And since it's going to point to the same place for empty and almost empty, they chose to point it to empty.


On the other hand, think about how stupid you'd have to be to run out of gas if your fuel gauge was accurate down to the last drop, instead of forcing you into a guessing game once the fuel light came on.
For something that everyone relies on at least once every month, it's weird that fuel gauges only actually convey information for the part of the gas tank when you need them the least, and are totally incapable of conveying information when you're on the verge of running out of gas on a desolate, serial killer laden wooded road.
It may not cost you money, but not knowing the difference between 5 and zero percent means that you have to spend 5 percent more of your life standing at a pump.



It's one of those ideas that seems smart in theory when it's controlling the behavior of those other idiots who can't handle the truth. But when you're late for a meeting and don't know if you have 40 or zero miles left before empty, it's harder to swallow.

But at least it's a mechanical error.
It's not like they're intentionally tricking us, like a dog owner pump faking a tennis ball, unlike ...

ronjenx

My first two vehicles didn't come from the factory with a gas gauge.
The truck I would flip up the seat, remove the cap, and look. (I had to squirt some oil on the valve train every once in a while, too.)
The VW Bug had a reserve lever on the front wall of the foot well. Drive until it sputtered, then flip the lever with the right foot. Start looking for a gas station. Back then there seemed to always be at least one in sight.

I never ran out of gas, either.

TURTLECON

All great comments! Learn something new everyday.

I should also mention my Aeroforce gauge reads % of fuel left. I've gotten it down to 2% before, but im guessing that reading could still be inaccurate if its simply reading the float level at "empty or almost empty". It would just be nice to know when the low fuel light is triggered how many actual gallons I have left instead of a guess.