Inaccurate fuel gauge?

[fluxpato]

So I understand that the electronic fuel gauge / "Miles Remaining" calculator isn't completely correlative to how much fuel is actually left in the tank. My previous fill-up I waited until my car read 13 miles remaining and then filled up, but was only able to put 8.3 gallons in the tank; what gives? Is this a defective unit or is it just a really inaccurate gauge installed in all 2011 2's? Also, does this mean that the MPG numbers given by the trip computer for Avg MPG/Current MPG aren't correct either? My MPG's have been awfully low for easy driving, and I'm curious if it's my car or the gauge that's got an issue...

 

[MazdaTwo]

So I understand that the electronic fuel gauge / "Miles Remaining" calculator isn't completely correlative to how much fuel is actually left in the tank. My previous fill-up I waited until my car read 13 miles remaining and then filled up, but was only able to put 8.3 gallons in the tank; what gives? Is this a defective unit or is it just a really inaccurate gauge installed in all 2011 2's? Also, does this mean that the MPG numbers given by the trip computer for Avg MPG/Current MPG aren't correct either? My MPG's have been awfully low for easy driving, and I'm curious if it's my car or the gauge that's got an issue...

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Click Here to jump over to a previous discussion about fuel gauge accuracy. A bunch of us noticed this right off the bat.

I don't know how it would affect the MPG readout on the computer, but for the sure the best way to keep track of your real life mileage per gallon is to always reset your trip odometer when your fill your tank. Then at the next complete fill-up, divide the miles driven by the gallons pumped and that will give you your MPGs. An easy way to keep track is with a website like Fuelly (link below).

So to recap: 1. Fill the gas tank completely. 2. reset your trip odometer. 3. drive until nearly empty. 4. Fill up the tank again, completely 5. Write down your trip mileage on your receipt. 6. Divide your trip mileage (ie, 350.3) by your gallons pumped (ie, 9.035) and you'll get your MPG (38.77). Or just plug in the numbers and Fuelly will do it for you.

 

[bluebomberx]

This is done by Mazda intentionally to extend the service life of the fuel pump. The pump will stay cooler if submerged in fuel. The remaining counter is set so that the pump remains submerged. My 2010 mazdaspeed3 and both our 2011 mazda2 behave in this manner, as well as the entire Mazda lineup now. It's a good thing.

 

[rchrist364]

Also the tank in 11 gallon tank. every time I go to the pump i barely get 9 gallons in. the other 2 are I’m guessing are not shown on the fuel gauge and are incase you run out. I’m guessing that is. I’m a delivery driver, I drive until the fumes.

 

[Mazdamatic]

ive noticed when i fill it up with only one bar left it fills up maybe 6 gallons. im guessing this is just mazda making sure you always have a filled tank.

 

[DrWebster]

This is done by Mazda intentionally to extend the service life of the fuel pump. The pump will stay cooler if submerged in fuel. The remaining counter is set so that the pump remains submerged. My 2010 mazdaspeed3 and both our 2011 mazda2 behave in this manner, as well as the entire Mazda lineup now. It's a good thing.

They've been doing this for years...my 2006 3 has a 14-something gallon tank, and I've only ever been able to put 11 gallons in. A smart move on Mazda's part IMO.

 

[Mazdamatic]

They've been doing this for years...my 2006 3 has a 14-something gallon tank, and I've only ever been able to put 11 gallons in. A smart move on Mazda's part IMO.

"better safe then sorry"

-unofficial Mazda quote that i just made up but im sure mazda would say something like this as it is better safe than sorry.

 

[JOE MAMA]

We've been having some funny computer related issues. Its happen twice now where we have filled up our 2 and the fuel gauge fails to register full and the DTE doesn't change either. Its seems to be some sort of computer glitch. It only seems to occur when we put between $5-$10 in. If the vehicle is close to empty, it will show all bars when filled.

Also, the other night I went to turn the car on and none of the interior dash/stereo lights came on. I have the headlights set to auto. The headlights came on, but no gauge lights (only the LCD screens on the odometer and radio which are always on). I ended up having to turn the car off an back on again to get the gauge lights to work (toggling the headlamp switch did nothing).