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Discussion Starter · #1 ·
Not sure if this is the proper forum or not but......

I have a new 2012 Skyactive and have a question about the gas tank capacity. The manual says 14.5 gallons (and I can find nothing anywhere to contradict that) It appears to me though that its a 12 gallon tank! Starting from a full tank it will empty normally and the low fuel warning will come on at 50 miles to empty. Today I ran it down to 5 miles to empty and filled it back up. It took 12.09 gallons. This is typical of the 10 or so times I have filled it. Other than the apparent decreased size of the tank the fuel gauge seems to be working fine. It is linear and pretty accurate.

Any thoughts?
 

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You have a reserve tank of 2.5 gallons the purpose of this is so you don't wear down the fuel pump and less likely to run out of fuel!
 

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Discussion Starter · #3 ·
Thanks!

I searched the forums and found an older thread that lead me to believe that was the case. I'll try not to go on a rant about incomplete instrumentation but I would really prefer to know EXACTLY how much fuel is in the tank!:mad 1:
 

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Thanks!

I searched the forums and found an older thread that lead me to believe that was the case. I'll try not to go on a rant about incomplete instrumentation but I would really prefer to know EXACTLY how much fuel is in the tank!:mad 1:
You AR better off as it is now, why risk your fuel pump or trying to press your luck on running out of gas as you drive into the gas station?

I agree. I'm finding that the 2011 M3 I recently bought has about 3 gallons left in the tank when I stop to fill it, when the remaining mileage is about at 0.
As Frnchplyr15 said its so you don't run out of gas.
 

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My gas light came on with about 60 miles to empty today, so I got gas. The pump clicked off at ~12.5 gallons, but I was able to get 14.2 in (just pumping slowly) before I voluntarily stopped for fear that I was somehow overfilling it...
 

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You were over-filling it, and it can damage the charcoal canister which is part of the fuel system. Best practice is fill it until the pump clicks off, squeeze the pump once more until it clicks off, then stop.

If the charcoal canister becomes saturated and is damaged as a result, it can cause reduced mileage and performance. Problems often show up in cruise when the evaporative system attempts to purge the canister of stored fuel vapors, which is its purpose, to store fuel vapors, not liquid fuel.
 

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My gas light came on with about 60 miles to empty today, so I got gas. The pump clicked off at ~12.5 gallons, but I was able to get 14.2 in (just pumping slowly) before I voluntarily stopped for fear that I was somehow overfilling it...
Holy crap man:shocked: thats way too much why would fill it up an extra 2 gallons! You do realize that when you fill it up the gas in the tank expands which can lead to cracks or even severe damage to your tank! I mean filling maybe half a gallon is still a lil worry some but do able but 2!!!!
 

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You were over-filling it, and it can damage the charcoal canister which is part of the fuel system. Best practice is fill it until the pump clicks off, squeeze the pump once more until it clicks off, then stop.

If the charcoal canister becomes saturated and is damaged as a result, it can cause reduced mileage and performance. Problems often show up in cruise when the evaporative system attempts to purge the canister of stored fuel vapors, which is its purpose, to store fuel vapors, not liquid fuel.
Westone hit it on the nose. That is also a safety shutoff at fuel pumps as to reduce the likely hood of spilling flammable gasoline on the ground in any significant amount. What was the motivation for continuing to fill past the safety shutoff anyways?
 

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What was the motivation for continuing to fill past the safety shutoff anyways?
To have more miles before that first bar hits probably lol
You were over-filling it, and it can damage the charcoal canister which is part of the fuel system. Best practice is fill it until the pump clicks off, squeeze the pump once more until it clicks off, then stop.

If the charcoal canister becomes saturated and is damaged as a result, it can cause reduced mileage and performance. Problems often show up in cruise when the evaporative system attempts to purge the canister of stored fuel vapors, which is its purpose, to store fuel vapors, not liquid fuel.
+1
 

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Moral of the story, don;t over fill gas tank it will damage charcoal canister along with some other un-named dangers and don't drive till you are virtually empty or you will cause damage to your fuel pump.. Trust me fill up when gas light comes on and at the max 0 miles left on the trip meter.. don't wait too long to fill up, there is a reason they designed it this way lol.
 

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Great thread here! I had always wondered what my reserve capacity was.

And I have always filled a tank until it cuts off then let it go a half gallon more, Its never a good idea to over fill a tank with 2 gallons!!!!
 

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Discussion Starter · #14 ·
The whole point in doing instrumentation is to do accurate and complete instrumentation. It's bad enough the car doesn't have oil pressure, oil temperature, and water temperature gauges and we have to trust the idiot lights but it rankles me that my gas gauge is so :argh 1:. There have been times when I have literally had to run cars to the last drop - fortunately always with a reserve can in the back. Same thing with nursing an almost dead car back to civilization, watching each nuance of the gauges for the telltale signs of imminent destruction.

Guess I better start searching for thread on aux gauges, eh! :cheesy:
 

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The whole point in doing instrumentation is to do accurate and complete instrumentation. It's bad enough the car doesn't have oil pressure, oil temperature, and water temperature gauges and we have to trust the idiot lights but it rankles me that my gas gauge is so :argh 1:. There have been times when I have literally had to run cars to the last drop - fortunately always with a reserve can in the back. Same thing with nursing an almost dead car back to civilization, watching each nuance of the gauges for the telltale signs of imminent destruction.

Guess I better start searching for thread on aux gauges, eh! :cheesy:
If you really want some instrumentation just get a scan guage II
 

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The whole point in doing instrumentation is to do accurate and complete instrumentation. It's bad enough the car doesn't have oil pressure, oil temperature, and water temperature gauges and we have to trust the idiot lights but it rankles me that my gas gauge is so :argh 1:. There have been times when I have literally had to run cars to the last drop - fortunately always with a reserve can in the back. Same thing with nursing an almost dead car back to civilization, watching each nuance of the gauges for the telltale signs of imminent destruction
Guess I better start searching for thread on aux gauges, eh! :cheesy:
If you have never run through the reserve in the gas tank before...why worry about it now? You do realize that even with analog gauges the reserve fuel was also taken into account?
 

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Discussion Starter · #17 ·
If you really want some instrumentation just get a scan guage II
or there are iPhone apps - scan gauge doesn't seem to do oil temp or pressure.

If you have never run through the reserve in the gas tank before...why worry about it now? You do realize that even with analog gauges the reserve fuel was also taken into account?
That depends on the car, some do - some don't. '91 Ford Explorer - Analog - 0 is 0 - you're out of gas. '94 Ford Explorer - Analog - 0 is 30 miles to go. 2001 Audi - Digital - 0 is 0 (again). So far I've only put 7 tanks of gas in, I'm trying to define the limits in case I ever do have to push it beyond.
 

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I don't see the issue here....I fill mine up based on mileage and if I'm taking a long trip, I look at the miles remaining.

I'm not sure why you need a precision fuel gauge.
 

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I dont even have a miles til empty thing. I always manage to get gas before the last little square/bar thing is gone.
 

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The whole point in doing instrumentation is to do accurate and complete instrumentation. It's bad enough the car doesn't have oil pressure, oil temperature, and water temperature gauges and we have to trust the idiot lights but it rankles me that my gas gauge is so :argh 1:. There have been times when I have literally had to run cars to the last drop - fortunately always with a reserve can in the back. Same thing with nursing an almost dead car back to civilization, watching each nuance of the gauges for the telltale signs of imminent destruction.

Guess I better start searching for thread on aux gauges, eh! :cheesy:
All those analog fuel gauges will vary model to model and even car to car with in one model. Every time I've replaced a fuel pump assembly (including gauge sender) it changed the way the fuel gauge read. In the end you learn the car and what level means what and it all comes out the same. Same goes for the temp gauges. An engines temp will swing 30-40 degrees in normal operation but that will never show on the gauge because it isn't accurate. In reality the gauge are only put there on some cars to make people feel more in control. If you want accurate gauges you have to go after market.
 
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