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Discussion Starter · #1 ·
So, today I noticed my fuel gauge drop to 4 bars (half full) and decided to check just how much gas I could add. Unfortunately, premium is rare here right now (Harvey hangover) so it took about 12 miles to find a station. At that time, I filled 9.25 gallons (U.S.), while getting about 24 mpg. It seems at half full, my car can take about 8.75 gallons without topping it off.

I searched by found no other reports, so I'm gonna try to fill up a couple of times at each bar level and figure the relative amount left at each bar. Now, anyone else that can report a fill up amount, no topping up, at a point where a bar has just dropped off your fuel gauge, please feel free to report it here.

I perceive that the first half of the gauge lasts longer than the second, a concept endorsed by my tank taking 8.75 gallons at the halfway point of a 15.3 gallon tank. This one encounter suggests that at the halfway empty mark, we have about 6.55 gallons left. I also believe the owners manual reported "reserve" is a blindly optimist amount with little basis in reality, as a fill-up a bit after one bar left was 14.35 gallons.
 

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So, today I noticed my fuel gauge drop to 4 bars (half full) and decided to check just how much gas I could add. Unfortunately, premium is rare here right now (Harvey hangover) so it took about 12 miles to find a station. At that time, I filled 9.25 gallons (U.S.), while getting about 24 mpg. It seems at half full, my car can take about 8.75 gallons without topping it off.

I searched by found no other reports, so I'm gonna try to fill up a couple of times at each bar level and figure the relative amount left at each bar. Now, anyone else that can report a fill up amount, no topping up, at a point where a bar has just dropped off your fuel gauge, please feel free to report it here.

I perceive that the first half of the gauge lasts longer than the second, a concept endorsed by my tank taking 8.75 gallons at the halfway point of a 15.3 gallon tank. This one encounter suggests that at the halfway empty mark, we have about 6.55 gallons left. I also believe the owners manual reported "reserve" is a blindly optimist amount with little basis in reality, as a fill-up a bit after one bar left was 14.35 gallons.
There is an older thread about exactly this. Your observations are correct and quite usual for the Quad (don't know which car you have but surely same with all Giulias). Personally I've found that when my gauge shows half full, I can put almost 10'gallons into the tank. I think the remaining range numbers are fairly accurate but that's just a sense after 2,000 miles. Have never tested it.
 

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Discussion Starter · #3 · (Edited)
I couldn't find the older thread, can you link to it?

So far:

F - 15.3
7 - 12.15 (-3.15)
6 -
5 -
H - 6.55 (-8.75)
3 -
2 -
1 - 0.55 (-14.75)
E -
 
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I couldn't find the older thread, can you link to it?

So far:

F - 15.3
7 - 12.15 (-3.15)
6 -
5 -
H - 6.55 (-8.75)
3 -
2 -
1 -
E -
I have yet to own a car which has an apparently accurate fuel gauge. There is one big complication though: what is "full" for the tank as intended by the manufacturer? In order to have evaporative emissions controls, the mfg does not expect that you will fill the tank to the very top. Even before evaporative emissions controls some dead space was required at the top of the tank to avoid thermal expansion of the fuel to cause the fuel to be expelled out the filler pipe (I remember seeing this happen in the 1960s). If you depend on the fuel pump fill valve shutoff to stop at the intended fill height you will find out that every fuel pump fill valve shutoff is different. I have observed about 3 gallons of fill variability from pump to pump when filling my Protege. To be rigorous about checking the fuel gauge calibration you need to drain the tank, then add fuel back in small increments and observe the fuel gauge reading. I suspect that this is what the manufacturers do to calibrate the fuel level sensor in the first place. It doesn't help you much to find the intended "full mark" on the tank though, unless you want to use the fuel gauge to decide when to stop the fill pump.

A more practical way to check your fuel gauge calibration is to run the tank below 1 mark. Then fill it 0.1 gallons at a time until 1 mark, then 2 marks, then 3 marks, etc appear on the gauge (ignition on, engine not running, of course). This won't give you the amount of fuel between completely empty and 1 mark, but it will check all of the other readings in a single fill up. You might need a helper to get this done in a reasonable amount of time--I don't know if you can see the fuel gauge reading while operating the fuel fill valve.

Taking your numbers:

15.3 gallon tank should be 15.3/8 = 1.913 gallons per mark.
You read 5.6 gallons difference between marks 7 and 4. The expected difference is 1.913*3 = 5.7 gallons. This seems pretty accurate and is within the measurement accuracy.

I strongly suspect that you are filling the tank up to 16.5 gallons of contents when you fill up, causing the time to reach mark 7 to be distorted. Likewise, I expect that every vehicle that I have owned was chronically overfilled (by myself, my wife, or an attendant) after a fill up resulting in a similar effect. Overfilling the tank is not a reflection of your skill but rather the limitations of the technology behind the fuel fill valve shutoff.
 

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Lockem posted: A more practical way to check your fuel gauge calibration is to run the tank below 1 mark. Then fill it 0.1 gallons at a time until 1 mark, then 2 marks, then 3 marks, etc appear on the gauge (ignition on, engine not running, of course). This won't give you the amount of fuel between completely empty and 1 mark, but it will check all of the other readings in a single fill up. You might need a helper to get this done in a reasonable amount of time--I don't know if you can see the fuel gauge reading while operating the fuel fill valve.


I tried this while re-fueling at Costco. All the drivers waiting behind me started laying on their horns! What the heck is taking you so long? :D

Seriously, I am very close to Costco (2 miles) and fill up there 95% of the time. I never top off the tank, but only
set the nozzle click stop to auto fill and let it turn itself off. Not a drop more. I then fill sometimes when the gauge
is at 50% or 25%, etc and sometimes let it get down low, just to the right of the empty bar. I then see how many
gallons to fill. So I get a good idea of how much gas I have left at 1/2, 1/4 and close to empty on the gauge.
I presume with my not topping off and always using their pumps with auto shutoff, I'm getting quite
close to actually using the 15.3 gal capacity. For example (I don't have my refill notes here), if I check 3 times at
close to the right edge of the empty bar and I average 14 gals per refiill then I know I have about 1.3 gals left.

I know I'm fortunate to live so close to Costco. Maybe y’all better move close to a Costco. There are 727 Costco's on Earth.
This link and photo might help! :p

https://www.statista.com/statistics/284431/number-of-costco-warehouses-2013-by-country/
 

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Discussion Starter · #6 · (Edited)
I understand the issue of differently calibrated auto-cutoffs, which is why I welcome anyone that filled right after a bar drops off to contribute the total added to the auto-cutoff. I intent to keep adding data to see if the points tend to herd at each level. If they do herd, we have useful data, if they do not, we understand that Alfa can't make a reliable fuel gauge.

With regard to overfilling, no. I have gassed up cars for over 35 years now and NEVER had a car with any failure on the evap system, a common problem overtoppers have. You are hoist by your own petard when you admit you've never had a car with an accurate fuel gauge and then use the half tank number to accuse me of overfilling by 1.2 gallons. I don't believe that level of overfilling is even possible.
 

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One red bar. 14.75 gallons. Gauge seems fairly linear.
 
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Lockem posted: A more practical way to check your fuel gauge calibration is to run the tank below 1 mark. Then fill it 0.1 gallons at a time until 1 mark, then 2 marks, then 3 marks, etc appear on the gauge (ignition on, engine not running, of course). This won't give you the amount of fuel between completely empty and 1 mark, but it will check all of the other readings in a single fill up. You might need a helper to get this done in a reasonable amount of time--I don't know if you can see the fuel gauge reading while operating the fuel fill valve.


I tried this while re-fueling at Costco. All the drivers waiting behind me started laying on their horns! What the heck is taking you so long? :D
Well thars yer problem...

I usually fill up at Sierra Energy in Jamestown. A nice little mom-and-pop that also sells homemade chocolate chip cookies. Just what I need for my weekly long drive. Downside is that their shut off valves cut off way too early.

In Santa Clara I am near several Costcos, but I don't like the busy-ness that they garner.
 

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One red bar. 14.75 gallons. Gauge seems fairly linear.
You need lots of points on a graph to demonstrate linearity. However your numbers are well aligned with the OPs and my conclusion that the fuel tank is getting filled to 16.5 gallons.

If the gauge and tank capacity were perfect you should need 15.3-1.9 = 13.4 gallons if you fill up immediately after you hit that last, red bar.
 

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I understand the issue of differently calibrated auto-cutoffs, which is why I welcome anyone that filled right after a bar drops off to contribute the total added to the auto-cutoff. I intent to keep adding data to see if the points tend to herd at each level. If they do herd, we have useful data, if they do not, we understand that Alfa can't make a reliable fuel gauge.

With regard to overfilling, no. I have gassed up cars for over 35 years now and NEVER had a car with any failure on the evap system, a common problem overtoppers have. You are hoist by your own petard when you admit you've never had a car with an accurate fuel gauge and then use the half tank number to accuse me of overfilling by 1.2 gallons. I don't believe that level of overfilling is even possible.
I did not accuse you or anyone else of anything; don't put words in my mouth. I just pointed out that your numbers are consistent with the tank getting filled to 16.5 gallons and that the gauge may be very precise. Another poster gave a different data point that is also consistent with the tank getting filled to about 16.5 gallons. I used both of your numbers to compute this value; one number is not enough. However, we now have 3 numbers and still come up with the same value: 16.5 gallons in the tank.

To be precise it is necessary to fill the tank from empty (drained, not empty on the gauge). I'm not sure anybody is going to want to do that.

I don't know of anyone who has had an evap system fail due to overfilling. That doesn't mean it never happens it only means that I don't know of it ever happening. I know of people who have had evaporative emissions control systems fail and that the mechanic blamed it on overfilling, but that is not the same thing especially since mechanics are trained to say that evap failure is always caused by fuel tank overfilling. I know the manuals for vehicles say "do not overfill or the evaporative emissions system may be damaged", but again that does not mean that it will be damaged.
 

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Discussion Starter · #11 ·
Just what I need for my weekly long drive.
First read through I "saw" whiskey vice weekly...left we wondering till I reread it.

Thanks for a datapoint, Chipshot...I suspect we should be hesitant about going to zero bars because of the pump cooling issue and the fact is may have only 10-20 miles range at that point...we'll see.
 

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..... In Santa Clara I am near several Costcos, but I don't like the busy-ness that they garner.
What the heck does that mean? :confused: :D
Even Bill and Jeff fill up at Costco! (Bill Gates and Jeff Bezos :wink2:)

We shop at Costco frequently. I use their no fee credit card for gas and get a 4% rebate.
That drops their usually lowest local price (by 10 cents or more per gal) for high
octane from for example $2.80 per gal down to $2.69. Big savings! 0:)

PS: Plus they sell a foot long hot dog and huge lemonade for $1.50! Wow!
 

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What the heck does that mean? :confused: :D
Even Bill and Jeff fill up at Costco! (Bill Gates and Jeff Bezos :wink2:)

We shop at Costco frequently. I use their no fee credit card for gas and get a 4% rebate.
That drops their usually lowest local price (by 10 cents or more per gal) for high
octane from for example $2.80 per gal down to $2.69. Big savings! 0:)

PS: Plus they sell a foot long hot dog and huge lemonade for $1.50! Wow!
I don't follow Bill and Jeff around to know their habits. It is at least a 5 minute drive to Costco, a 5 minute drive back from Costco and a wait in line at Costco. I can't buy a homemade cookie at Costco, but if I buy a huge box of cookies it is another 10 minutes of walking and waiting. Compare with Sierra Energy which is a 10 second drive out of my way, a 10 second drive to get back on my way, 20 seconds to grab a cookie on my way out of the restroom and I have never had to wait in line for gas. If I save $0.15/gallon on a 10 gallon fill up at Costco I saved $1.50 and it cost me 10 to 20 minutes of my time. So I earn $4.50 to $9 per hour--less than minimum wage. That is without factoring in the 1/4 to 1/2 gallon or so burned driving to and from Costco.

I don't want a hotdog and huge lemonade in the middle of my weekly road trip. 1 cookie exactly "hits the spot".

Maybe it works out better for you, but it does not work for me. I can't and did not speak for anyone but myself.
Oh yeah, I use my Costco card at Sierra Energy and get 3% back, so some of the price difference is not real.
One more: if I fill up in Santa Clara, I will need to get gas in Walker in order to make the round trip, and gas in Walker is about $1/gallon more than in already pricey Santa Clara. Maybe Giulia's larger fuel tank will work around that issue, but only if the average fuel economy is also good; I won't know until I get my car (due Dec 4).

Costco works great when buying in bulk. If I was filling a 100 gallon tank in a Motorhome the economics look better for filling up at Costco.
 

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First read through I "saw" whiskey vice weekly...left we wondering till I reread it.

Thanks for a datapoint, Chipshot...I suspect we should be hesitant about going to zero bars because of the pump cooling issue and the fact is may have only 10-20 miles range at that point...we'll see.
I second that point. No clue if 0 bars is 5 miles of range or 60 miles of range. If the transition from 1 to 0 bars means there is only 0.7 gallons in the tank we get the linear behavior of the bars and a 15.3 gallon tank capacity. That doesn't seem likely though.

I can't see draining the tank just to make this measurement. However, if someone has to have their tank drained to fix something, maybe they can make the measurement without invoking a major hassle.
 

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I don't want a hotdog and huge lemonade in the middle of my weekly road trip. 1 cookie exactly "hits the spot".
I see your point. Time means money!

I'm actually a huge chocolate cookie monster but I buy them up here at Safeway. They are so good I go out of my way to buy them, nice and soft. I'm retired. However, they have raised them for a two pack from $1.00 to $1.29 and now to $1.59 all in just one year. I hate Safeway and now am now going thru chocolate cookie withdrawal counselling. It's six months long and covered by my insurance plan

BTW, Pete Carroll and Mark Zuckerberg also buy gas at Costco!

:wink2:
 

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I see your point. Time means money!

I'm actually a huge chocolate cookie monster but I buy them up here at Safeway. They are so good I go out of my way to buy them, nice and soft. I'm retired. However, they have raised them for a two pack from $1.00 to $1.29 and now to $1.59 all in just one year. I hate Safeway and now am now going thru chocolate cookie withdrawal counselling. It's six months long and covered by my insurance plan

BTW, Pete Carroll and Mark Zuckerberg also buy gas at Costco!

:wink2:
LOL. I suspect that Sierra Energy just buys manufactured dough and cooks them in house, but they are pretty good. Last night the owner was in line at the register (at her own store!) to buy something but backed up when I approached the line. I fussed that she was ahead of me and should go first (before I saw who she was). She told me to have the cookie on the house.

I was shocked 25 years ago during a business trip that took me to London to find a Safeway there. All of the other stores were closed on Sunday; something about having to pay a fine to be open on Sunday.

There is at least a finite chance that I will cross paths with Mark in Santa Clara. I suppose Elon Musk just plugs in. I suppose if he were to drive to Hawthorne he might take the same route that I take, but it seems more likely that he would fly. I'm not much of a name dropper anyway...

It might be noted that many people obsess about the price of gas, but in reality it is a small portion of the cost of owning and operating a car.
 

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Has this thread managed to end up as satire? If yes, I applaud your sharp wit. If it truly has ended up about cookies, I don't know what to think.
Fuel tank marks leads to fuel filling leads to fuel stations which often make most of their money selling snacks so the discussion digresses to snacks.

Anyway I would not advise that anyone see how far they can drive after the gauge drops to zero marks so unless someone wants to take the time to drain their tank and then use a measuring device to refill it I think we have most of the answers.

Summary of actual information about Giulia so far:

15.3 gallon tank on 8 marks fuel gauge -> 1.913 gallons per mark.

Marks 7, 4 and 1 on the fuel gauge are multiples of 1.9 gallons apart (measured). It seems likely that the other marks are similarly accurately spaced. More data points are certainly invited.

Filling from 0 marks on the fuel gauge in tiny increments (or if you can see it while filling, stopping each time the number of bars on the gauge changes) to measure all of the marks in one go is not recommended at a busy gas station, such as Costco due to the time involved. Someone with the right car and right gas station is encouraged to make said measurement.

The tank probably holds an "extra" 1.2 gallons beyond the stated capacity that is ABOVE the 8th mark on the gauge instead of below the 1st mark as such reserves are implemented on many tanks. Alternatively, the tank may have very little capacity once it drops to 0 bars.
 

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Discussion Starter · #19 ·
I'm not in agreement about 1.9 per, not enough data.

The manual says 2.38 gallons (U.S.) or 9 litres, and you get the fuel symbol and a chime. Now, that puts paid to the 1.9 per, unless they are suggesting you have almost half a gallon left at the zero bar point, and the last bar is 1.9 gallons...and Chipshot's data doesn't match that. We'll see as more data trickles in.
 

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I'm not in agreement about 1.9 per, not enough data.

The manual says 2.38 gallons (U.S.) or 9 litres, and you get the fuel symbol and a chime. Now, that puts paid to the 1.9 per, unless they are suggesting you have almost half a gallon left at the zero bar point, and the last bar is 1.9 gallons...and Chipshot's data doesn't match that. We'll see as more data trickles in.
The manual says 2.38 gallons for what?

Let's do the math again, since I am certain about the 1.9 gallons per mark both as what it is supposed to be and what it is:

Assuming that both you and Chipshot fill the tank to the same height:

Reading Gallons to full Gallons in tank
F N/A unknown
7 3.15 unknown
6 N/A unknown
5 N/A unknown
H 8.75 unknown
3 N/A unknown
2 N/A unknown
1 14.75 unknown
E N/A unknown

(8.75-3.15)/3 = 1.87
(14.75-3.15)/6 = 1.94
(14.75-8.75)/3 = 2.00

Unless bars 6,5,3, and 2 are highly irregularly spaced, this is pretty close to 1.9 gallons per mark. The slope of the best line for the 3 data points is 1.94 gallons per mark. What we don't have to be able to fill in the gallons in tank column is the intercept because we don't know how many gallons really fit in the tank. However, if we assume 1.9 gallons per mark with an intercept of 0 gallons in the tank we get a nice alignment with all of the observations so far

Reading Gallons to full Gallons in tank Experimental
assuming 16.5 capacity Error (gallons)
F N/A 16.5 -
7 3.15 13.3 0.15
6 N/A 11.4 -
5 N/A 9.5 -
H 8.75 7.6 0.15
3 N/A 5.7 -
2 N/A 3.8 -
1 14.75 1.9 -0.15
E N/A 0 -

Gallons to full is the amount of fuel a properly setup automatic fill shutoff valve will put in the tank immediately after the fuel gauge has dropped to the noted mark. That is Chipshot put in 14.75 gallons when it dropped from 2 to 1 bars. Chipshot did not run it down to truly empty so we only have conjecture regarding how much fuel and how much usable fuel he has in his tank when he added 14.75 gallons.

Also, 1.9 gallons per mark isn't the number that fits the data, it is the number that fits Giulia's specification: 15.3/8 = 1.9125. It also happens to fit the data.

I expect this is a situation similar to AR stating that the 2.0T has 280HP. It actually does have about 280 WHP with presumably more at the flywheel of the engine. Likewise, I think that 15.3 gallons is the most AR says you can reliably use from the tank without significant risk of sucking air into the fuel pump rather than the actual amount of fuel that can fit in a properly filled tank or the amount of fuel that you can pump out of the tank while the car is perfectly level and stationary. However, the fuel gauge is telling you how much fuel is actually in the tank rather than how much you can reliably consume from the tank.
 
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