36 Gallon Tank Reserve?

[LuisCarrillo91]

So I left my 3.5 Ecoboost truck till it showed 9 miles to empty and I filled it and it took 30.246. I was wondering is the reserve about 5-6 gallons?

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[1sick21]

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[discothan]

I was told by the service tech that there is no physical reserve tank, it is just programmed to give you a visual of 'Distance To Empty' and give you some safety to get to a gas station.

 

[LuisCarrillo91]

I was told by the service tech that there is no physical reserve tank, it is just programmed to give you a visual of 'Distance To Empty' and give you some safety to get to a gas station.

So does my truck have the wrong tank size then? Because I know the powerboost have 30.5 gallon tank size. Interesting. Does anyone had the same amount of gallons filled when truck is showing around 9 miles to empty.

 

[Blue Spruce]

I’ve noticed the same thing on mine. 36 gallon tank and the last few times I’ve filled up I had about 30 miles to empty and only put in about 28-29 gallons. I’d expect a few gallon “cushion” on the distance to empty but 5-6 gallons seems like a lot. My 2016 also had the 36 gallon tank and when I’d get down to 20 miles to empty I was putting in 32-33 gallons.

I wondered the same thing about whether it had a smaller tank the last time I filled up. I double checked the window sticker and it clearly says 36 gallon tank with the max tow package. I can’t imagine them putting in the wrong tank.

also, the MPG shown on the dash when I refilled was off by about 20% so I thought maybe I accidentally reset a trip meter. But, it’s cold now and I have a bunch of short trips and some remote starts and winter gas so I’m not expecting great mileage at the moment.

I was tempted to throw a 5 gallon can of gas in the back and run it dry to see how big the tank really was but not sure that is a good idea....

 

[Bryan Simon]

The sending unit on these things are probably the same on all three/four tank sizes.
having 5 gallons when zero miles shows up on a 36 gallon tank, might only be thee on a 30 gallon tank, and maybe 2 on a 23 gallon tank.

Changes to this probably would need to be made in the software somewhere
Not sure if I would concern myself with it too much unless I were one to run the tank dry.
Also, less concern when she comes in saying the truck has read "0" miles left since last monday.

 

[Pedaldude]

with older analog gauges, I have noticed that reserve can vary between identical vehicles, same for calibration of the gauges. My last truck, an 06 Silverado was fairly accurate but other vehicles I have had experience with, half a tank on the gauge could be a quarter tank. Still with others, when the light comes on, it could be as little as a few miles, to as much as 20-30 before you finally run dry.

In modern trucks with digital readouts, I have found they’re usually pretty accurate. My Lincoln is spot on, when you reach zero miles, you might have two miles to go if you start nursing the throttle and it’s relatively flat. The light on the analog gauge comes on with around 15-20 to go. I know it’s accurate after running it dry once pulling into a gas station. It was bucking when I took a few fast turns and the fuel sloshed around and it just started missing on level ground when I turned the key off at the pump.

It’s not good to run low on fuel long term, people who habitually run their tank empty can damage the fuel pump, which depends on its immersion in fuel for cooling and sometimes lubrication. You can also damage the engine running it on low fuel pressure for lengthy periods of time but running out of gas is usually fairly sudden and at low throttle openings, so the ECM should be able to compensate.

The short answer is that running out of gas once shouldn’t do anything to your gas powered vehicle. The problem is safety, especially if you live somewhere where there’s not many safe spots to pull over.

However, I have purposely run every single one of my new vehicles extremely low on gas where either I could hear the pump gurgling, feel the engine sputtering or simply have it stall altogether at least once to know exactly how much range I can expect and if the gauge is reliable and accurate. I will normally trust the trip meter more than the gauge until I get a feel for things.

Assuming 20MPG, a 5 gallon reserve will be 100 miles, that’s excessive and defeats the purpose of a fuel gauge because after you reach zero, if there’s still 100 miles of range, you will be going off the odometer, which is a little less accurate, since a headwind or “false flat” grade can hurt mileage over a longer period of time. Other than in a few spots, I have noticed that on the interstate, even in extremely rural areas, there’s a gas station every 5-15 miles and a 20 mile reserve is a handy safety for when you need to be reminded that you better stop at the next exit.

Hopefully, something can be figured out. Otherwise, hypermilers have installed secondary computers that measure the actual pounds of fuel consumed per hour, though that seems a little excessive too.

I ordered a truck with a 36 gallon tank, so I’ll need to wait and see!

 

[N1TJ]

So I left my 3.5 Ecoboost truck till it showed 9 miles to empty and I filled it and it took 30.246. I was wondering is the reserve about 5-6 gallons?

The way the Owner's Manual reads is that the increments at which you're alerted of low fuel is dependent on the way you drive. More aggressive driving warns you sooner since your forecasted fuel economy shows you'll be "dry" sooner than if you were being conservative with better MPGs.

 

[Bryan Simon]

I havent seen the low fuel light in my Ranger since it was relatively new.
My goal was to get 400 miles out the tank, and the light came on about 10 miles shy of that.
if I recall--18 gallons to fill it after. 20 gallon tank
I tend to fill right at 1/4 regardless.
And on both trucks I will guess what it will take to fill them before I start.
My guess usually within 1 gallon.

Once I get those 1/4 and 1/2 marks figured out---wont need the miles remaining.
Now I am filling alternate trucks every other week end.
Saturday morning coffee, and fuel, so I really don't monitor fuel levels too much---I fill out of habit.
SHE, on the other hand, waits til the low fuel light comes on.
When we first started living together, took me year to get her to fill the tank.
She had been putting $5 at a time in for so long and she never filled up. Old habits die hard.
I cannot remember the last time I did NOT fill the tank.

 

[Kino]

For humor - I am going to get this on a shirt for my Dad! He's the left; I am the right.:

 

[discothan]

Assuming 20MPG, a 5 gallon reserve will be 100 miles, that’s excessive and defeats the purpose of a fuel gauge because after you reach zero, if there’s still 100 miles of range, you will be going off the odometer, which is a little less accurate, since a headwind or “false flat” grade can hurt mileage over a longer period of time. Other than in a few spots, I have noticed that on the interstate, even in extremely rural areas, there’s a gas station every 5-15 miles and a 20 mile reserve is a handy safety for when you need to be reminded that you better stop at the next exit.

Keep in mind MPG rating is lower under load/towing/4x4.

I don't mind the early warning, gives me a bit more wiggle room when towing an RV.
The comment about the wife telling you 5 days later about the gas light...LOL....so true.

 

[Pedaldude]

The computer will quickly extrapolate the estimated miles remaining if you’re towing, driving 90mph or going around town in stop and go traffic. I don’t think the OP was towing or drag racing, so who knows, if under those conditions; the computer will still be ignoring the remaining five to six gallons.

on the 36 gallon tank we’re only talking 1/6th of a tank but for the 23 gallon tank it’s over 1/4 tank. That’s great for the absent minded or cautious but it’s not good if you want to know how much fuel you actually have left in your tank without having to fill all the way up.

Around town that extra five gallons might just be 30lbs of dead weight and a little extra security but on a cross country trip it’s going to be an unnecessary stop at a gas station that might be in an expensive or undesirable spot. Even worse, off-road, it might mean turning around when you don’t have to.

is there anybody who has had the 36 gallon tank in an earlier generation truck?

 

[daemonic3]

is there anybody who has had the 36 gallon tank in an earlier generation truck?

Yes, I always ignore the 50 mile DTE warning and then take the 25 mile warning as "time to get gas when convenient". It usually will only accept 33-34 gallons. I don't remember it EVER taking more than 35.

That being said, I never really could do exact calcs as I have to run my card twice at most california pumps due to so many pumps having the (now way out dated) $75 security limit per swipe. We have been over $3/gal for probably 10 years so this limit is sooooo annoying especially when I cannot get my card company to NOT flag my card if I fill up outside my nearby zip codes. I have to have 2 different cards handy due to all this annoying "protection". (Discover, Chase, and Citi all seem to do this even though they offer gas cashback incentives)

 

[LuisCarrillo91]

I called Ford Tech service and they told me that it has a 5 gallon reserve tank. Hmm does anyone want to try?

 

[daemonic3]

I called Ford Tech service and they told me that it has a 5 gallon reserve tank. Hmm does anyone want to try?

WHAT?!?! There's an extra 5 gallons of useable fuel just sitting around under there? Yes, please someone who definitely is not me give this a try!

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