So i was getting low on my fuel gauge and my mileage indicator said i have 25 miles left. Well with in 5 miles it went to 0 miles left and then i ran out of gas, my question is where does the computer get its information on miles left from the fuel gauge ? What could be off the sender in the tank not accurate ? Or is it using the overall life average fuel mileage ?
Ran out of gas! 2008 LTZ
- Thread starter ridewot
- Start date
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pretty sure it is a best guess with the computer. some of it depends on how you drive.
if you suspect the float may be wrong then replace the fuel pump.
my 18 will do the same thing when it say's 25 remaining and then goes to just "low" then you better find a gas station real quick.
you kinds gotta keep in mind if you typically get 12-15mpg and it tells you that you only have 25 miles to go, that means you have a gallon maybe a smidge more which means take it easy and find gas, it's probably not going to make it exactly 25 miles......
that will do it, if you were on flat land and just feathering the pedal it might have gone farther.
I don't know particularly on these trucks but on our stuff at work, it's 100% based on the adv fuel mileage. after a while ours get down to like 2mpg because they just sit idling for hours on end and maybe drive a mile per month and the low fuel warning will go off when the tank is full because it thinks it's got less than 50miles left to go, even thou it's got 3/4 to full tank.
I gotta reset the life meter all the time because people thank it's running out of fuel and won't use it. call the fuelers and they say it won't take gas. all while the gauge is right there reading correctly lol.
if you're going to tow long distance and want the miles left to be correct, you gotta reset the fuel mileage before you hop on the interstate.
I gotta reset the life meter all the time because people thank it's running out of fuel and won't use it. call the fuelers and they say it won't take gas. all while the gauge is right there reading correctly lol.
if you're going to tow long distance and want the miles left to be correct, you gotta reset the fuel mileage before you hop on the interstate.
iamdub
Full Access Member
I think it uses the level sensor in the tank as well as averaging the injector flow rate, vehicle speed, time, etc.
I watch my vitals closely to proactively spot issues and can fairly accurately calculate the fuel's alcohol content based on MPG. So, I'm very familiar with the actions of my fuel gauge. For a few months, I found that when I was around 1/4 tank or less and accelerated hard from a stop, it'd bog, nose down, then come back to life. It'd immediately be resolved once I added fuel and would repeat when the level got back down, getting worse the closer to "E" the gauge read.
The pump is in a bucket that should stay full even if the tank level is low. I thought the bucket was leaking, leaving the pump at the mercy of the fuel level in the tank and the fuel was sloshing to the back on those hard accelerations. I dropped the tank to replace the entire pump assembly (~200K, so why not?). When I started the job, the gauge read 1/4 tank. When I dropped the tank, I found it had maybe an inch or so of fuel in the bottom- much less than 1/4 tank.
After installing the new pump module, the gauge was hąrd on "E". I tested the original level sensor and found the impedance scaled as it should for the first ~3/4 of it's travel down from full. Then, somewhere around 1/4 tank, it'd go to infinite/open circuit. What was happening was that I was much lower on fuel than I was lead to believe and was running the bucket dry since it couldn't replenish from the tank during accelerations.
If the gauge relied solely on level sensor in the tank, it would've plummeted from 1/4 tank to "E" when the fuel got that low. What it does, maybe as a backup, maybe as a smoothing function or maybe as some other function, is uses calculations to estimate the remaining amount of fuel. When the fuel is that low, its calculated guess can only be so accurate, especially if driving like an ass. Or, in your case, pulling a trailer. MPG and miles to empty is constantly being averaged. Pulling a trailer for 50 miles compared to the hundreds or thousands of miles prior unloaded means that trailering mileage will be a very small factor in those calculations. Idling returns 0 MPG, so that will drag down your average MPG calculations. As soon as you start driving again, it should recover fairly quickly and the longer you drive, the more accurately it'll calculate your driving MPG. Since the fuel level is constantly changing, this won't (can't?) be as accurate.
You running out of gas could be due to this or a failed/failing fuel level sensor or a combination of both.
petethepug
Michael
In general this Gen of truck has an OEM f/p known to run over 100k miles. As a general rule you’ll want to start shopping for a replacement OEM f/p after that benchmark. Check out R/A and Parts Geek for the best pricing on OEM lifetime guarantee pumps. You’ll pay 2-3x less than a local part house. DO NOT use generic f/p. They have a 12-18mo life span.
If you haven’t done so yet remove the carbon pellet emission canister at the back of the truck and replace it too. This is the age when the barrier that holds the pellets in breaks and lets pellets into the fuel system creating havoc.
If you haven’t done so yet remove the carbon pellet emission canister at the back of the truck and replace it too. This is the age when the barrier that holds the pellets in breaks and lets pellets into the fuel system creating havoc.
On the bright side, at least you were driving a V8 Tahoe pulling a trailer. Imagine how embarrassing running out of gas would be if you were driving a Prius.
Marky Dissod
Full Access Member
The moment you saw that it said it had 25 miles left, you should have already been pulling into a gas station.
In a '94 Caprice wagon I once owned, the engine quit with 1/4 tank of gas shown on the gauge.
The Caprice was pointing uphill, nose up. None of the fuel in the tank could reach the fuel pump.
I rolled the wagon downhill in neutral until it reached level ground.
On level ground, the fuel in the tank covered the pump again, so I started it, and drove to the gas station.
Later I learned that I could also 'run out of gas' with 1/4 tank shown by taking on-ramps / off-ramps too fast. The engine would stumble and quit, the car would slow down, the fuel would resettle, I'd restart the engine and get moving again, this time gently.
To oversimplify the answer to your questions:
If the fuel gauge shows 1/4 tank or less, assume the range is 60 miles or less, and tank up.
Fuel pumps are like fish - they need to be kept swimming in fuel.
Yes. I also track miles. I know how many miles I can get to a tank on the highway, around town, and when towing, so I'm always checking my fuel gauge against my miles driven on a tank. I do this because I was once left stranded on the side of the road with a 4 year old Land Rover LR3 that told me it still had 1/4 tank of gas left but was in fact, empty. That, and the fact that as a pilot, we're taught to never trust fuel gauges.
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