Reserve indicator inaccuracy?

[unicycle]

A few people have recently written similar posts in a different thread, so I decided to start a new thread:

I recently filled up WITHOUT topping off. A few days later, I filled 'er up again. The fuel indicator LCD showed that I had .7 gallons left. The fill-up showed I'd just put in 8.5 gal WITHOUT topping off. This suggests one or more of the following:

1. The gas station was ripping me (and everyone else) off by having its pumps click more than they should have.
2. The indicator is off by a pretty big amount. Basically, I was running on fumes if this is the case.
3. My tank mysteriously holds more than 9 gallons.
4. There is something I need to learn about filling up my car.

Any help?

[wahi]

I had a similar experience. 0.1 gal in reserve mode is about 0.5 gal at the pump.

[SmartDigger]

In Ohio , a stations pumps are considered accurate if they are +/- .1 ( 1 tenth) of a gal. I have a scangauge that is dead on at one station I use the most. if I fill up ( Vibe) and the scangauge said I used 10 gal. the pump will shut off at 10 gal. At another station the pump always pumps more about .5 -.8 gal more than scangauge said I use.

[timhood]

Every time I've filled up, gas put in plus what dash gauge said I have left was always less than 8.7 gallons. If it was ever more, I'd seriously question the accuracy of the pump. At these prices, the temptation to steal from customers has to be greater than ever. Next time you're at that station, see how long ago the pump was certified.

BTW, my wife drove it all the way to 0.0 once recently when she didn't have money with her (cash or credit card). She filled it the next day, so I don't know how much she was able to put in.

[bumblebee]

My reserve indicator didn't even go off and I put in 8.344 gallons yesterday. So now I wonder if the station I used had faulty pumps.

[tverb]

On the gas filler flap on the smart it says "DO NOT TOP OFF".
Topping off risks damage to an evaporative gas filter.
So, I don't "top off"!

[Commander Cody]

And don't forget about where you are driving. When the tank shows .5 or .4 or whatever is left and you are driving up and down in the mtns. you better get ready to run dry....real fast.

[SmartDigger]

also the volume of gas changes with temp. gas volume expands as temp goes up

[unicycle]

Originally Posted by SmartDigger

also the volume of gas changes with temp. gas volume expands as temp goes up

That's a good point, and when I most recently filled up, it was a really warm day. However, I'm not sure that this affects the gasoline entering the car (if I remember correctly, this notion has been debunked at SCOA already). It may affect the readout from what's left in the car, but I doubt that, too. So maybe that isn't a good point after all....

[spdickey]

The variable here is when the nozzle shuts off. Do not assume that all nozzles will shut off at the same level of gas in your tank. The difference may be one gallon or more.