How accurate are gas pumps?
 

Put 25.9 gallons in my 25 gal tank today :(.
I don't think I was on fumes either...always push the limit, and only on one other occasion have I ever topped 25 before. I know they are "supposed" to be accurate at any pressure, etc. but how do we know for sure?

Now I want to put 26 gals in...living on the edge :)

It's totally fun until that time you guess incorrectly!!!

Good question though. I assume there's some kind of allowable tolerance.

I know that here in NY the state certify that they are pumping the posted amount. And if not the station will be fined big time. They send inspectors around to check out the pumps.

Your tank is not 25 gallons. It is designed to fit the space allotted for it not to hold a nice round number. I have removed tanks from cars and trucks that read well below empty and still contain a gallon or two of fuel. The filler neck itself can hold a gallon and the design of most tanks leave an air space at the top. I would guess the actual volume of a 25 gallon tank is more like 27-28.

Few years back, they discovered a scam where the pumps were set to accurately dispense the quantities that the inspectors tested for, but shorted quantities over and under.

I think the testing has been changed to use random fill amounts now, but not for sure on that.

I'm sure there's a hotline where you can report, or file a complaint through the inspector office?

Regularly running around with your tank that low is a great idea if you enjoy replacing fuel pumps.

Fuel pumps are cooled by the gas they are submerged in.

When you run too low they overheat leading to premature failure.

One thing in a car where typically you can access it from inside the car.

Quite another in trucks / SUVs where a tank drop is required.

YMMV

In one of my undergrad design classes, the instructor said that gas pump meters were one of the worst types of meters available. I have personally pumped 5.5 gallons into a 5 gallon can.

How accurate are gas pumps?
 

As a owner of a gas station, I can assure you that the gas flows in the great republic of California are tested, monthly (we hire a compliance company to test), quarterly (compliance co & county inspector), and annually ( compliance & county inspector). So in all we are tested 17 times a year. The temperature can also play a role in volume of gas dispensed...


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In Ohio the county is responsible for testing the pumps. The pumps have calibration stickers on them that are dated, but to tell the truth I've never looked at them closely enough to see the dates, but I think they are tested annually. They fill a calibrated 5 gallon container and must be within .5 percent of accurate to pass.

So in conclusion, they are very ****ing accurate.

<iframe width="602" height="295" src="https://www.youtube.com/embed/h5UMvzf6xOI" frameborder="0" allowfullscreen></iframe>

That is probably a good example of why he is an instructor and does not make a living in the real world.

The positive displacement volumetric meter used to measure fuel at the pumps is very accurate, very predictable, simple and holds calibration for a long time.

It would make allot more sense to question the accuracy of your 5 gallon can.

Go back and look at the can. It has a fill level. You can easily put a 1/2 gallon in above that level if you pump it to the top.

I know all of this, yet I'm not changing my ways after 40+ years of driving and at least 200 fill ups in that truck with less than a gal to spare :)
Did completely run out one time as I rolled into the station, but didn't fill up that particular time. I also realize the capacity is more than 25, but I still think that particular pump wasn't calibrated properly based upon the fuel guage reading and prior history/track record of 24+ gal fill ups...jmo

One of these days I may be posting another "sofa king" thread....until then, I'll be

Living on the edge :)

cool video!

Not trying to divert this thread...but what about the pricing on the diff grades of gas?
A few years back there was always a 40 cent diff from reg to prem. Lately that diff has changed to 60 cents. This past week when filling up..I found a $1.00 diff from reg to prem. What is going on??:confused:

Dated, but informative:


U.S. Energy Information Administration (EIA)

In my YOOT I was much the same way. I wouldn't fill up until I absolutely had to.

Then I paid for a new fuel pump and two new catalytic convertors on my 86 for furd ranger and decided running on fumes was a bad thing.

Nowadays I rarely get under 1/4 tank (approx. 7 gallons). I figure one of these days the big one is gonna hit, and assuming I can find roads open I want to have the ability to drive from work to home or home to ????? without having to loot some gas 'cause all the pumps will be down.

Who knows how long that drive might take, but the worst case scenario would be to get stranded in long beach after a major quake with looting and such, and not have any gas or spoons or ammo to take out the zombies and dips ;)

Since we have 4 cars (me, wifey, daughter, son) I figure at any one time I can siphon together at least one whole tank of fuel but I'd still have to get home to get it (32 mile drive).

I rarely hear anyone say "I wish my gas tank wasn't so full" ....

Gas meters are pretty damn accurate but...
Gas volume changes quite a bit with changes in temperature. Hint: Fill up in the morning.

Also, the teenager that filled ahead of you may have shut off the pump and gravity-drained another 1/2 gallon from the hose into his tank. When you started, the pump had to refill the hose first before getting gas into your tank. (don't ask how I know this trick) .

I hate to say it but Sammy is right in this thread. :)

Also, I'm only seeing the usual ten cent difference between grades of gas here in Los Angeles, for the most part. The exception would be a loss leader station downtown that is giving away 87 octane to have that lowest price sign up but making up for it on mid and premium which are 50 cents more.

My dad was a *keep stocked up* kind of guy and he always had a year's supply of paper towels, toothpaste, etc. When his car got down to half a tank, he had to fill it. No exceptions. Like he had a phobia about running out of anything. I'm not like that but I don't test my fuel gauges like I did when I was young and broke, either. :cool: