How much fuel do I REALLY still have...?

[Jack in Prescott]

I'm new to Ford products so please square me away on this issue. I use my 2021 Powerboost to tow a 5000# trailer some of the time. With almost 1/4 of my estimated range remaining on the fuel gauge, I stopped to refuel and - Surprise! - took 29 gallons. Yikes! The problem, of course, is that Fred (hey, that's his name ...) learned what my mileage was when NOT towing and then didn't adjust when my mileage dramatically changed as he began dragging this trailer behind him. I didn't even get a 'warning light' from the fuel gauge, probably because it was happy using the indicated mileage. The manual offers me no way to simply select a 'Gallons' reading, at least that I can find. It seems to me, in trying to make it do my fuel thinking for me, Ford almost left me by the side of the road. Do I understand the issue accurately? And any work arounds other than refueling generously?

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[CaptainAmericaRob]

I was told by a calibrator a couple years ago, that they calibrate "zero" with 1 gallon in the tank.

In my 2019 Ranger and my 2015 F150, I have driven 3-5 miles past "0 MILES TO EMPTY" a few times to get to a gas station, wth no issues. (dumb i know ?)
Note: there's also, nearly a gallon in the lines from the tank to the engine

 

[BHunted1]

I was told by a calibrator a couple years ago, that they calibrate "zero" with 1 gallon in the tank.

In my 2019 Ranger and my 2015 F150, I have driven 3-5 miles past "0 MILES TO EMPTY" a few times to get to a gas station, wth no issues. (dumb i know ?)
Note: there's also, nearly a gallon in the lines from the tank to the engine

Don't know about today's vehicles, but gas tanks usually have a reserve tank. It's internal...

 

[Pedaldude]

There's no physical 'reserve' tank, it's all about the calibration of the gauge and the float position. Some trucks have more reserve than others. My Dodge van and Dakota pickup basically had maybe a gallon left in the tank when the gas light came on and you had better be near a gas station when it did. My Silverado had a generous enough reserve that didn't have to worry about running out of gas, I think it was two, maybe even two and a half gallons once the light came on. On my Lincoln Navigator, the range on the trip meter is dead-on, so when the light comes on with a little over 50 miles of range left, I can be sure that when the range hits zero the engine will be sputtering!

My V8 truck has the 36 gallon tank and the one time I refueled with around 20 miles left of range, I only was able to fit a little over 28 gallons in the tank. The 7 gallon reserve is what I consider excessive and there's some speculation that it is because Ford did a bad job of designing the tank baffles and fuel pickup in the 36 gallon tank and people's trucks wouldn't start sometimes when parked on grades.

Most motorcycles will have a petcock with two settings and two separate fuel pickups to provide a fuel reserve so that you don't run out of gas. Generally you will reset the odometer and keep track of miles too, since a lot of motorcycles weren't built with fuel gauges. I do the same with my trucks and it helps if the fuel gauge goes out. With all the loose connectors on 2021 trucks, it's probably a good practice.

 

[sbi]

......learned what my mileage was when NOT towing and then didn't adjust when my mileage dramatically changed as he began dragging this trailer behind him.

I highly dout this is how it works. I don't think your vehicle "learns" how much fuel it consums when it first hit the road after production, I believe the engine's computer (one of them) knows how much fuel is burned at each minute of the engine running. Of course the tank's float adds to the calculation but I don't think it learns and uses it as a mpg data.
Disclaimer: I am not a mechanic or Ford engineer. Hack, I don't even have my truck yet

 

[pkinneb]

My concern with the PB towing a 5000# trailer is that even a gallon or two at 8-10 mpg is really not much

 

[WestcampTX]

I was told by a calibrator a couple years ago, that they calibrate "zero" with 1 gallon in the tank.

In my 2019 Ranger and my 2015 F150, I have driven 3-5 miles past "0 MILES TO EMPTY" a few times to get to a gas station, wth no issues. (dumb i know ?)
Note: there's also, nearly a gallon in the lines from the tank to the engine

Toyotas are calibrated to where you have like 75 miles when you hit zero. I personally find that super annoying.

 

[ATLalien]

I'm new to Ford products so please square me away on this issue. I use my 2021 Powerboost to tow a 5000# trailer some of the time. With almost 1/4 of my estimated range remaining on the fuel gauge, I stopped to refuel and - Surprise! - took 29 gallons. Yikes! The problem, of course, is that Fred (hey, that's his name ...) learned what my mileage was when NOT towing and then didn't adjust when my mileage dramatically changed as he began dragging this trailer behind him. I didn't even get a 'warning light' from the fuel gauge, probably because it was happy using the indicated mileage. The manual offers me no way to simply select a 'Gallons' reading, at least that I can find. It seems to me, in trying to make it do my fuel thinking for me, Ford almost left me by the side of the road. Do I understand the issue accurately? And any work arounds other than refueling generously?

I don't have the answer but have noticed a similar issue. I towed a small pop up camper for 600 miles RT. Typically the range on a full tank is over 600 miles, I noticed when topping up the tank mid trip the range had dropped to 500 miles and change. After we came home, I parked the truck for several days, then went out and refilled the fuel. My range was still showing only 500 and change even though I was no longer pulling a load. However, as I drove, the range started to go up rather than down until it finally equalized. The truck does "learn" (if you want to call it that) enough to change the range calculation based on recent fuel economy. It seems there can be a delay in range adjustments too, until the data catches up. However, it doesn't seem that the actual fuel gauge is affected by this, just the range calculation.

 

[mj1angier]

I "think" the miles till empty is a running calculation. I have noticed it go up and down depending on if I have been driving in ECO vs when I put a trailer behind the truck on the same tank of gas. I belive that my truck the low fuel warning comes on with about 2 gal-ish left in tank

 

[Bandito]

The low fuel warning comes on when you have 50 miles left to go according to the DTE calculation. If you are using MyKey, it warns at 75 miles.

On my 2018 F-150 EB, there was a setting in the dash for the DTE calculation: one for normal usage and one for towing. I tried them both, but didn’t really notice any difference. I‘m not sure if the 2021’s still have this setting or not. I’ll have to look for it.

The DTE caclculation is very simple. It’s just current mileage times fuel remaining. I’m sure that they add a little filtering/smoothing to the calculation to keep the DTE from varying every time you hit the throttle, but I can’t think of anything that they could do to account for trailer towing other than perhaps removing some of the smoothing so it reads a lower DTE sooner. I’m sure that there’s a Ford engineer or two out there that could explain all this, but unless they’re here on the forum, we’re unlikely to ever find out. ?

 

[Jack in Prescott]

Thanks for the comments, everyone. ATLalien did a better job of summarizing what I'm asking about than I did.
"The truck does "learn" (if you want to call it that) enough to change the range calculation based on recent fuel economy. It seems there can be a delay in range adjustments too, until the data catches up."

However, the last sentence conflicts with my own experience:
"However, it doesn't seem that the actual fuel gauge is affected by this, just the range calculation."

My fuel gauge was showing just under 1/4 tank with the range estimate being pretty consistent with that fuel level, and yet I put 29 gals into my 30 gal PB tank when refueling. I guess my takeaway is: 'When towing, assume ~10 gph fuel consumption and refuel well before 300 miles.

Or as pkinneb stated: "My concern with the PB towing a 5000# trailer is that even a gallon or two at 8-10 mpg is really not much."
It sure isn't. Still pondering how to deal with a hoped-for 2022 Alaska trip, towing the trailer, for some of the more remote sections on the route.

Jack

 

[EatDirtFartDust]

Ford has always been that 0 DTE means 1 gallon left.
About the OP’s issue, I’ve driven many ford trucks that gave me an option for dte calculation being calculated for towing or not.
I haven’t searched on our trucks yet, but I bet there’s a setting to make your DtE more accurate when towing.

 

[Gulfstream]

Just asking, but. . . You are sure that you don't have the heavy duty towing package with the 36 gallon tank?

 

[Pedaldude]

I don't think that they offer the 36 gallon tank in Powerboost, it has something to do with the hybrid battery. Pretty sure because of that, PB gets its own unique tank.

 

[EatDirtFartDust]

The power boost gets a 30.5 gallon tank.
Maybe it’s 31.5?
It’s not 36, that wasn’t available.

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