Overly conservative gas gauge

draco_m · Mar 9, 2015

The 2014 Cruze has a 15.6 gallon tank I believe. When my “low fuel” light goes on the computer says I’ve only used 11.8 gallons. I pull into a gas station and fill up. Car holds about 12 gallons so computer was pretty accurate.
That means the low fuel light goes on with 3.8 gallons remaining. That’s way too conservative for me. I can certainly see 2 gallons as a “cushion” but not 3.8. That’s well over 100 miles of driving.
I know I can keep on driving and just ignore the low fuel light and gas gauge on “E.” But that’s frustrating because the low fuel reminder keeps chiming.
Are other people having a similar experience with their gas gauge/low fuel light?

au201 · Mar 9, 2015

It is conservative, but it is like that for a reason. Running your tank really low habitually is very bad for the fuel pump because the fuel pump has to be submerged in gasoline to cool itself properly. You should fill up before the low fuel light, or at least right on it. I normally fill up at a quarter of a tank or a little under. Keep in mind that still leaves me over 300 miles in between fill ups...the 3 gallon cushion isn't so much for you as it is the continued functionality of your fuel pump. I would not advise you ignore it and keep driving...

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draco_m · Mar 9, 2015

au201 said:
It is conservative, but it is like that for a reason. Running your tank really low habitually is very bad for the fuel pump because the fuel pump has to be submerged in gasoline to cool itself properly. You should fill up before the low fuel light, or at least right on it. I normally fill up at a quarter of a tank or a little under. Keep in mind that still leaves me over 300 miles in between fill ups...the 3 gallon cushion isn't so much for you as it is the continued functionality of your fuel pump. I would not advise you ignore it and keep driving...

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Thanks. That makes sense. I did fill up right away after the light went on. So the tank never went below 3 gallons. The range on the Cruze is good. Even if I only use 12 of the 15.6 gallons I'm looking at about 400 miles in mixed driving.

jblackburn · Mar 9, 2015

FWIW, both of our cars from 2 different manufacturers leave about ~3 gallons of a "reserve" once the light comes on. I've seen my Cruze take on 12.6 gallons when the light comes on, and once put in 13 gallons (I think the light comes on based on your average MPG and speed for the past X miles - more of a range thing)

If people had 1 gallon left, they'd just run themselves out or go up a hill and slosh all the gas away from the pickup and then be angry and say the car is at fault.

Aussie · Mar 9, 2015

I often put 50 litres of diesel in my Cruze and the low fuel light hasn't come on. That leaves me a reserve of 10 litres (2.6 gallons US), and still no light.

dhpnet · Mar 10, 2015

I agree that the low fuel warning comes on too early and is overly annoying. It also stops displaying the distance to empty and just shows LOW. I have gone below E and still had about 2 gallons in the tank.

If the goal was to stress you out and cause so much anxiety that you couldn't delay filling up, then the engineers did a great job. But that means that the tank really only holds about 12-13 usable gallons.

I don't understand why the engineers would use a fuel pump that requires the fuel to keep it cool. I have had other cars with electric fuel pumps that were not cooled by the fuel. Seems strange to me.

spacedout · Mar 10, 2015

dhpnet said:
I don't understand why the engineers would use a fuel pump that requires the fuel to keep it cool. I have had other cars with electric fuel pumps that were not cooled by the fuel.

Never have seen a car that doesn't use fuel to cool the pump. If your talking about an external(not in tank) in line electric fuel pump, those are also cooled by fuel flow.

spacedout · Mar 10, 2015

draco_m said:
The 2014 Cruze has a 15.6 gallon tank I believe. When my “low fuel” light goes on the computer says I’ve only used 11.8 gallons.

Do you have and ECO manual transmission? Remember they have a restriction that kicks the pump off earlier, so it only holds 12.6 gallons in the 15.6 gallon tank. Also have noticed even without this restriction my 1LT 15.6 gallon tank can have up to a half gallon variable when the pump kicks off. This is easy to see if you fill up at a few different stations. Can only imagine a slow fill on an ECO tank could introduce even greater error since there is even more available capacity beyond when its designed to kick off.

Have only taken my car near the low fuel warning 4 times, every single time my 2012 1LT auto goes off at 13.1 gallons burned, leaving a 2.5 gallon reserve of the 15.6 gallon tank. With such a large tank on a high MPG car though I can drive 10-12 hours before I ever need gas, so no reason at all to run the tank so low. I certainly need to stop for rest room or food/drink well before that.

Merc6 · Mar 10, 2015

Good catch. Depending on pump and how many times you go after 1st click off, it varies for me between 11 and 12 before I have to trickle fill to 15 or so gallons.

jblackburn · Mar 10, 2015

Had a Buick Century where E literally meant E. When the gauge dropped into the Orange zone, the car started chugging and surging like it was about to run out. I don't know how big the reserve is on an Escape, but my sister has managed to run her car out twice.

I'd rather have the reserve.

spacedout · Mar 10, 2015

In highschool I tested my 1987 chevy celebrity(2.5L iron duke) low fuel range, I even put a gas can in trunk. Drove 70 miles with it on E before it ran out of gas. With this info assumed with a 1/4 tank in my 1986 buick lesabre(3.8L) I should be able to make it 10 miles to the city for fuel, 4 miles down the road the car ran out of gas with the needle resting on 1/4 tank still.

Completely agree I would rather have reserve. If you fill the cruze 1LT 15.6 gallon tank at 1/4 tank, its about 10 gallons burned. Would rather fill up with 5 gallons reserve than only the 2.5 GM designed into the car. One should figure worst case scenario MPG for reserve capacity, so those 5 gallons X 19MPG = only 95 mile range. Yes my worst top off was 19MPG!!! Cold start, winter with tons of idling/remote start, think my average speed was only 17mph.

NickD · Mar 10, 2015

This only happened once with my Cruze, normally consider a quarter full tank and empty tank as that over pushed fuel pump needs all the cooling it can get.

But a long day, knew I had enough gas to get home, and that low fuel light came on when I pulled in. Filled it up the next morning, took 13.6 gallons and this is the way its suppose to be. Two gallons remaining.

This is what the fuel pump looks like.

See that long narrow tube under the float, a thermistor is located in there that gets hot when the fuel drops below it, a positive indication of low fuel and should go on with two gallons left. Bet when they installed yours, they bend that tube so your low fuel level light goes on sooner. Either this, or some idiot made your tube too short.

spacedout · Mar 10, 2015

NickD said:
Normally consider a quarter full tank and empty tank as that over pushed fuel pump needs all the cooling it can get.

Agree 1000X.

Hit a chunk of ice on the interstate that fell off a semi in front of me, ripped hole in metal gas tank of my 1991 Buick lesabre. Because I typically have as full of tank as possible I was able to continue driving 4-5 miles to the next exit and gas station before I ran out of fuel. Can only imagine if my tank was not full I would have been ran over as my car died at 75mph in the interstate.

If you get stuck in traffic or on a snow covered interstate parking lot a car could easily burn a gallon or more an hour idling. Which would you rather have, an empty tank or an almost full one? lets say you hit the low fuel warning on the cruze and then get stuck in traffic for an hour, you could have less than a gallon left to get you to the gas station once moving again.

In the winter I top off my tank between 1/2 and 3/4 tank, one other advantage is I only have to stand outside 2 minutes at best pumping fuel so don't even have to put on a heavy coat or gloves. The few times I have ran my tank to 1/4 tank in the winter its 6 miserable minutes of freezing my ass off pumping fuel.

NickD · Mar 10, 2015

For years, GM speedometers and fuel gauges sucked for lack of a better word. When half full, in reality was less than a quarter of a tank. Speedometers were always around 10% low.

Fuel gauge was a major problem during the so-called energy prices, couldn't even buy a half a gallon if your fuel tank showed half full. And all the talking in the world at the then full service gas stations wouldn't change this.

Speedometer on my Cruze matches my GPS precisely, and looking at my gas gauge, know exactly how much fuel it should take.

Ha, remember filling up at a station, where the pump said I used 4 gallons more, complained about this to that minimum wage clerk, like talking to a wall. But filed a complaint on my credit card, and got a full refund.

We use to have a weight and measurements guy come around, but he was canned due to budget cuts as well as the FTC.

BigNorm4Life · Mar 10, 2015

And if you have to like I did, if your gas light is on and you really need to know how much gas you have left.. Go to the DIC menu that actually tells you how much gas went thru the engine, my gas light comes on after I used 13 gallons of gas respectively. Subtract 13 from 15.6 and its simple math from there. If I gotta run it down to E, I fill up at 15.3 used

spacedout · Mar 10, 2015

Thats good to know. I actually have never used that screen, last time I looked it was reading thousands of gallons I have ran though my car.

NickD · Mar 10, 2015

Top off the tank get in and put on my safety belt, ignition to run so don't have to listen to that ding ding ding.

Rotate the knob on the end of the directional level.

Instantaneous MPG, who cares.

Average MPG, hit the button and reset it,memorize the number.

Fuel Used, reset that to zero, but compare that to what the pump says. Last time was identical, but not always, whose lying, the DIC or the pump. But usually within 0.5 mpg, and the pump is always higher, think I am getting screwed.

Odometer 2, skip that, only reset that after an oil change.

Odometer 1, reset that, gives the mileage since my last fillup. Do the math mentally.

When we switch to summer gas, coming soon, should be now, getting summer weather, miles remaining may say 440, but still says 440 or even higher after driving 50 or more miles.

May say 640 miles before we switch to winter gas, but when we do, drops faster than jumping off the Empire State Building.

ChevyGuy · Mar 11, 2015

It wouldn't surprise me but what the "E" light is set so that you can drive the longest stretch of road to get to a gas station before you run out. The lawyers would have made sure of that. Otherwise they would require a warning label for the light.

Overly conservative gas gauge

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