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Gas Gauge/Low Fuel Light/Range Estimation Question

Tom Craig

New member
Update: Every time I fill up I reset my "trip B" to zero so I always know how far I've gone on a tank. So far the trip and the "range" indicator haven't matched up in that the "range" would tell me that I should be getting almost 500 miles out of a tank. Today I noticed that the range was far more conservative and was down to about 415 miles to a tank which is a lot closer to accurate. I wonder if this will improve as we go?
 

Deere78

Well-known member
Update: Every time I fill up I reset my "trip B" to zero so I always know how far I've gone on a tank. So far the trip and the "range" indicator haven't matched up in that the "range" would tell me that I should be getting almost 500 miles out of a tank. Today I noticed that the range was far more conservative and was down to about 415 miles to a tank which is a lot closer to accurate. I wonder if this will improve as we go?
Those miles to E rangers are never right. All the vehicles I’ve owned they are always generous. It’s estimated off fuel economy average. I’ve found that they are always off.
 

JTaylor62

Well-known member
OK, regarding how many miles the display says you have versus what you really have. I now agree - a calibration issue. Regarding how big the tank is, I don't know but I do know the capacity is higher than what's posted. As I noted earlier in this thread, if you want to top off the gas tank - fill it slowly. Also, I agree with the earlier thread - never let your gas tank get below 1/4 tank. The gas actually cools the pump. And to agree with the earlier thread - it does prevent water freeze up. 87 versus 89 versus 93 in the V6. I don't care what the manual says, I know what I feel - and 89 runs better. Finally, I also noticed not all gasolines are the same. For me Shell is the best. But FCA does recommend (as well as most other manufacturers) that you use top tier gas (check out this link to find who sells it): https://www.toptiergas.com/licensed-brands/

As far as MPG - does any manufacturer actually achieve what they post? OK, if you drive your vehicle under optimal conditions - say: in a straight line (and a super smooth road) with 0 incline with no wind in 75 F weather at 55 mph - then maybe you'll hit it. I've never had a vehicle that even came close (except when I had a diesel).
 

Sarge

Well-known member
Those miles to E rangers are never right. All the vehicles I’ve owned they are always generous. It’s estimated off fuel economy average. I’ve found that they are always off.
My BMW's keep counting you down to the last few miles. I've seen my prior 2007 X5 go all the way down to zero one time (and it made it one more mile for fuel). The fact that this one says 'fifty', and then two miles later you can put 25.3 gallons in a 23 gallon tank... They need to address this.
 

Sarge

Well-known member
Just another data point: Yesterday, I was at my dealer, and the fuel light came on. It went from '48 miles remaining', to 'low fuel'. I then drove 2.8 miles at 55mph to the nearest gas station, and put 24.85 gallons in my 23 gallon tank.

Something's just not adding up.

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MBeach

Member
OK, regarding how many miles the display says you have versus what you really have. I now agree - a calibration issue. Regarding how big the tank is, I don't know but I do know the capacity is higher than what's posted. As I noted earlier in this thread, if you want to top off the gas tank - fill it slowly. Also, I agree with the earlier thread - never let your gas tank get below 1/4 tank. The gas actually cools the pump. And to agree with the earlier thread - it does prevent water freeze up. 87 versus 89 versus 93 in the V6. I don't care what the manual says, I know what I feel - and 89 runs better. Finally, I also noticed not all gasolines are the same. For me Shell is the best. But FCA does recommend (as well as most other manufacturers) that you use top tier gas (check out this link to find who sells it): https://www.toptiergas.com/licensed-brands/

As far as MPG - does any manufacturer actually achieve what they post? OK, if you drive your vehicle under optimal conditions - say: in a straight line (and a super smooth road) with 0 incline with no wind in 75 F weather at 55 mph - then maybe you'll hit it. I've never had a vehicle that even came close (except when I had a diesel).
Yes, mileage estimates have to be fairly accurate or a manufacture is sued and loses every time. Small variances are ok, but I am barely achieving 21 mpg, and my driving is 95% interstate. A difference between 21 highway and 25 highway is almost 100 miles per tank. My 2019 Silverado LT TB averaged 22 miles per gallon, and it was lifted 2 inches on mud tires. 21 mpg from a V6 powered mid size suv is pathetic.

Something is messed up in the tuning for the engine. It seems the engineers failed to even account for cruise rpm between 60-80 mph. Every other modern car I have driven has achieved its highest fuel mileage in this speed range, but this Jeep struggles to make epa estimate on highway on flat ground with no wind.

I’m praying that as the motor breaks in, fuel mileage gets better. If not, this Jeep will quickly leave my stable.
 

Mike1597

Well-known member
Just another data point: Yesterday, I was at my dealer, and the fuel light came on. It went from '48 miles remaining', to 'low fuel'. I then drove 2.8 miles at 55mph to the nearest gas station, and put 24.85 gallons in my 23 gallon tank.

Something's just not adding up.

View attachment 1909

This article will likely explain what is happening.

The vehicle's fuel tank capacity does not include the vapor headspace (that portion of the tank compartment at a level above the filler pipe neck) or the volume of the filler pipe. Sometimes drivers ignore the pump nozzle's automatic shut-off and continue to hold the nozzle operating the lever open in an attempt to deliver additional fuel. When this happens, the additional fuel begins to fill the vapor headspace and the filler pipe that are not considered part of the tank's rated capacity, thus resulting in a delivery of fuel greater than the fuel tank capacity rating stated in the owner's manual. Similarly, the lanes that surround the service station pumps may not be level and fuel may shift into the vapor space thus allowing more fuel to be delivered into the tank.
 

Sarge

Well-known member
I am 'topping it off' so to speak, so that may answer why I'm getting more than 23 gallons in. However, I'd really like to know how many gallons I'm supposed to have left once the fuel light comes on. Seems I'm going to have to drive it until the light comes on, and then drive it until it runs out of gas, then throw a couple gallons in from a jerry can and fill it up the rest of the way at the nearest station just to figure that out.

I haven't found in the owners manual where it tells you how many gallons you're supposed to have left when the fuel light comes on.
 

Mike1597

Well-known member
I am 'topping it off' so to speak, so that may answer why I'm getting more than 23 gallons in. However, I'd really like to know how many gallons I'm supposed to have left once the fuel light comes on. Seems I'm going to have to drive it until the light comes on, and then drive it until it runs out of gas, then throw a couple gallons in from a jerry can and fill it up the rest of the way at the nearest station just to figure that out.

I haven't found in the owners manual where it tells you how many gallons you're supposed to have left when the fuel light comes on.
Owner's Manual Page 109.
Low Fuel Warning Light When the fuel level reaches approximately 2 gal (7.5 L), this light will turn on and a chime will sound. The light will remain on until fuel is added
 

Sarge

Well-known member
Thanks. I'll put no-ethanol fuel in with the pump on the slower setting and let the pump auto-stop as soon as the light comes on next time. That *should* equate to 21 gallons, assuming 'topping it off' (putting 25 gallons in in the past) is essentially squeezing in a couple extra gallons to fill the expansion reservoir.

Still, I've put 23 gallons in shortly after the light came on in the past, just using the auto-stop on the pump. I guess we'll see (I generally don't like to run it below 1/4 tank in winter especially due to potential for condensation).
 

Sarge

Well-known member
Another data point: Today, I stopped to fill up with the marker just a tick above the 1/2 tank mark. It took 13.5 gallons before the pump auto-stopped, and I topped it off at 17.1 gallons total.

So, the sensor is DEFINITELY not calibrated correctly. If I have a 23 gallon tank, and the gauge says just a bit over half, it should take about 11 gallons, not 13.5, and definitely not 17.1. Worth adding that this was partial 'ethanol' gas (like 10%), which has a tendancy to cause bubbles when filling and trigger the autoshutoff prematurely.

If the expansion reservoir is 2-3 gallons (extra you can squeeze in for topping off), then that would mean I put in 14-15 gallons with the gauge reading slightly over half, in a 23 gallon tank. So, it's wrong no matter what.

The concerning thing is we rely on it to be accurate ESPECIALLY when it gets to the lower end of the tank... and worse than underestimating, it's overestimating how much fuel is left.
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GRN ENVY

Active member
Guage is definietly wrong, and the dealer doesn't know what to do for mine. I drove down to 35 miles to empty, light wouldn't come on, I pulled into the gas station next to my house, shut the car off, turned it back on. The light magically came on and said "low fuel". That point my DTE was no longer giving a reading. So shut it off and I filled up 22.3 gallons. So I had less than a gallon, and was approximately getting 20 mpg. No way I would have made it 35 miles.

I'm in buy back talks, so hopefully one of you can get it rectified, and share the solution in the near future.
 

Sarge

Well-known member
The lowest I've seen to date was 48 miles remaining when the fuel light came on. I drove two miles at 55mph from the dealer to the nearest gas station, and put in 24.85 gallons. I've put in as much as 25.1 previously. Since my fuel economy says 12.9mpg (horrible), if there were two gallons remaining it should have read '25 miles remaining', but said 48 when the light came on (this V8 couldn't get 24mpg if it was on a tow truck.

Still, If you consider that I only drove a couple miles at 55mph, there should have been roughly 2 gallons left in the tank at the point I put 25 gallons in it, meaning I have A 27 gallon fuel capacity. Which seems impossible, even if the expansion reservoir accounts for a couple of extra gallons (which will fill if you pump slowly).

What this tells me is my 'low fuel' light comes on when there is less than a gallon left, which is dangerous in rural Wyoming, especially in winter when it can be -20F at times (-15F so far this year). I don't generally run my car that low, but my wife does it all the time.

Worse, when I filled it with just over a half tank showing (post above), it took on 17.1 gallons, which means it is simply not reading properly. Given the long distances between gas stations, mountain passes and cold temps where I live, it's really bad having a substantial overestimate of how much fuel you have on board, especially at a half tank or less. Basically, a half tank is more like 1/4 tank, and 1/4 tank might only be a few gallons remaining.

It should go without saying that engineering an accurate fuel gauge should be an achievable feat of engineering in 2022... yeesh.
 

GRN ENVY

Active member
The lowest I've seen to date was 48 miles remaining when the fuel light came on. I drove two miles at 55mph from the dealer to the nearest gas station, and put in 24.85 gallons. I've put in as much as 25.1 previously. Since my fuel economy says 12.9mpg (horrible), if there were two gallons remaining it should have read '25 miles remaining', but said 48 when the light came on (this V8 couldn't get 24mpg if it was on a tow truck.

Still, If you consider that I only drove a couple miles at 55mph, there should have been roughly 2 gallons left in the tank at the point I put 25 gallons in it, meaning I have A 27 gallon fuel capacity. Which seems impossible, even if the expansion reservoir accounts for a couple of extra gallons (which will fill if you pump slowly).

What this tells me is my 'low fuel' light comes on when there is less than a gallon left, which is dangerous in rural Wyoming, especially in winter when it can be -20F at times (-15F so far this year). I don't generally run my car that low, but my wife does it all the time.

Worse, when I filled it with just over a half tank showing (post above), it took on 17.1 gallons, which means it is simply not reading properly. Given the long distances between gas stations, mountain passes and cold temps where I live, it's really bad having a substantial overestimate of how much fuel you have on board, especially at a half tank or less. Basically, a half tank is more like 1/4 tank, and 1/4 tank might only be a few gallons remaining.

It should go without saying that engineering an accurate fuel gauge should be an achievable feat of engineering in 2022... yeesh.


It should be easily engineered. My previous vehicle was an F150 with a 36 gallon tank. It stated exactly at 50 miles to empty the light would come on. It actually had more range, because the light would come on at 50 to go, which was roughly 5 gallons left. That cushion was nice to have on long road trips, and rural driving.

This Jeep has been 100% a disappointment and massive miss by FCA/ Stallantis/ Jeep. Looks great and has all the right bells and whistles. Execution of it all. A miss.

8900 miles on my Jeep now, and consistent fill ups of 21 gallons with 70 miles to empty. I'm not acheiveing 35 mpg. I've hand calculated ~20 to 21 MPG. Filling up at 70 miles to empty with 21 gallons means I should have around 40 miles to go.

Hope Jeep is having engineers and prgrammers read this thread.
 

Sarge

Well-known member
I put ~25.9 gallons in it yesterday (topping off, autoshutoff at 22.5 gallons). That means I had maybe 1/2 gallon left (my wife was driving it and probably drove 5-10 miles before I filled it). I live in rural Wyoming, where it's a dangerous thing if you run out of gas (can be -20F this time of year), and she never thinks to put gas in any car until the idiot light comes on. It's actually dangerous, as there are considerable stretches of road with no cell service, and no safe place to pull over either (canyons and mountain passes).

I'd at least like to know the 'topped off' capacity so I can calculate how much is really left when the fuel light comes on, and I'd like to program it to say 'low fuel' when it says '80 miles remaining', because to date the lowest number I've seen is 48 miles remaining. At 13MPG (or less if you're driving over mountain passes), the supposed two gallons (per the manual) is only 26 miles remaining, not 48. On top of that, there might only be a gallon remaining, which could be just 5-10 miles around here.

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JTaylor62

Well-known member
I still believe the tank is bigger than specified. I think the real tank is closer to 28 gallons. If you fill the tank real slow - so the air gap isn't a factor you can get more gas in the tank. I have put 28 gallons in my 26 gallon RAM.
 

Sarge

Well-known member
There's an expansion reservoir that isn't really meant to be filled (but you can if you go slow), and I'm guessing that might be 2-3 gallons. Lat time, the auto-stop on the pump allowed 22.5 gallons, which might bring me to 23 gallons, and if the expansion reservoir is 2-3 gallons plus the filler neck (filling slowly to top off), that's how I assume I get to 26 gallons of fuel, meaning the totally full capacity, if you ran it dry, might be 26-27 gallons (with the expansion reservoir and filler neck).

Nevertheless, the gauge is not remotely accurate if I can put 17 gallons in with it showing a bit over half a tank. Even if you subtract 3 gallons for the top off, that's 14 gallons at over half full indicated, which would equate to a 28 or 29 gallon tank instead of 23. That's a pretty big error. How long have we been manufacturing gas gauges now? Sheesh.
 

Badgerdon

Well-known member
Makes one wonder if it’s not a calibration issue between the sending unit in the tank and computer that controls the dash. When the low fuel light comes on the vehicle should have about 50 miles left to empty. Which should be approximately 2.5 gallons or so. Luckily my wife is pretty good about filling up before the 1/4 tank. I on the other hand have a bad habit of seeing how far I can push it. I will not be pushing my luck in the jeep that’s for sure. Lol
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