Fuel Lesson Learned

[Chops]

Back in the 70’s as a starving student at the U of A , the gas tank on my 1970 Chevy Nova was rarely above a quarter tank full. When running on fumes I knew a $1 worth of cheap gas would get me to class & back from my off campus house 15 miles round trip. 200hp small block V8 with 12mpg and gas @$.60/gal.

50 years later I’m a “well fed” (I’m not fat!!) retiree who fills the tank when half empty for ~$30. Tank never goes lower half full.

In modern cars you are risking electronic fuel system failures by running your car down to nearly empty.

I’m truly fascinated by grown men (who aren’t starving) will feel motivated to get their gas tanks levels as low as a ‘70’s student.

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[Cancunbadlands]

I put on my villain cape, and I do 3 extra squeezes while twirling my mustache

No, no, no you will damage the Ford evap system and throw a code

 

[grandpa_disney]

Ouch! Word of advice. Your fuel pump needs gas in the tank as coolant. It pushes gas up to the hot engine compartment, the engine uses what it needs and the rest, after picking up not only heat from the pump pressure but now the engine compartment, heads back to the tank. With low volume in the tank now, the pump's "coolant" is not doing what the pump needs it to do!
You should never run the tank, at least on purpose, below a quarter full. I sold lots of fuel pumps to folks who ran their tanks consistently low or filled when the warning light came on. What ate em up? Overheating! Save yourself a costly repair and fill er up sooner!

Life was much simpler when we had mechanical fuel pumps.

 

[Darryl]

2025 XLT AWD Hybrid. Pulled into refuel with 40 miles on DTE indicator. Low fuel warning came on at exactly 50. Truck took 13.4 gallons (13.8 capacity). Much too fine for me. I will refuel in the future before the 50 mile low fuel warning in the future.

1. The tank Actually holds more than 13.8. I actually ran mine to zero. It held about 14.5
2.DTE is based on your driving up to that point. If you change it drastically , it won’t be accurate.. My Truck was reading 70 to empty. But the last 100 miles had been city driving . I had a 45 mile trip and was running late. It was ALL highway 75 mph driving . The DTE dropped like a rock after I passed the last gas station. I drove about 6 miles on zero DTE . When I got to the next station, it held about 14.7. By the way, I was probably about 1/2 mile from my destination. So the 70 mile DTE of optimum driving turned into 45 at 75 mph.

 

[Bret Grabber]

And then again in my prior 6 vehicles over 35 years, I was almost always running down to the fuel light coming on, if it had one (usually meant 2 gal left), or below the E line - unless I saw prices going up and just had to get in early.
And except for 1 - all used vehicles with 80K or higher starting mileage when I got them.
VW, Nissan, Mazda, Fords, Toyota.
Never had a fuel pump issue. Carb to FI of some sort.
Always in city with good fuel options though, didn't do the scary stations. Tried never to fuel-up when their tanks were being filled.
3 of those older vehicles, and current Mav - seen in the repair manual where the pickup line was in the tank, and where pump sat - to never have a concern over cooling due to placement.

I'm now going to add the PID for temp on pump just to see in scan data.

You've been lucky! I retired as a Commercial Parts Specialist at our local Advance Auto Parts Store in 2018, topping off a 50 year career running from gas pump jockey to tech rep for a major performance parts manufacturer. Spent the final 8 years with Advance supplying local repair shops with parts service.
One of the trends I noticed was the number of electric fuel pumps my customers ordered. A couple of the good ones would preface the order with, "I have another one that never fills their gas tank!"
I had unfortunately learned that lesson a few years prior when I was traveling the country as the tech rep, pulling a 24' box trailer with a 1990 Ford F350, 460 gas engine with dual tanks. I habitually let the rear tank go to "E" before switching to the front. At 80,000 miles I replaced the original pump. Also had to replace the harness as the connector was all but burned up. Just 20,000 miles later I had to replace both again for the same reason! That's when a contact told me about the cooling requirement of the pump! From that point I never let any fuel tank go under 1/4 full. I sold that truck at 169,000 with that secont fuel pump and the original front tank pump still going strong. I never let the front tank run under 1/4 full.
The only other one I've replace was in a 2001 Dodge that I used to pull my race car all over the eastern US while traveling my sales territory for a motorsports company I repped at the time. I had removed the box to repair some rust issues at 129,000 and with the pump right there in the open, I replaced it as a maintenance function. I then used the old one for a home made parts washer for two years, heavily filtered, of course! I traded that truck in 2013 with 169,000 miles on it.
Just my two cents based on experience!

 

[MakinDoForNow]

1. The tank Actually holds more than 13.8. I actually ran mine to zero. It held about 14.5
2.DTE is based on your driving up to that point. If you change it drastically , it won’t be accurate.. My Truck was reading 70 to empty. But the last 100 miles had been city driving . I had a 45 mile trip and was running late. It was ALL highway 75 mph driving . The DTE dropped like a rock after I passed the last gas station. I drove about 6 miles on zero DTE . When I got to the next station, it held about 14.7. By the way, I was probably about 1/2 mile from my destination. So the 70 mile DTE of optimum driving turned into 45 at 75 mph.

Yes the MTE is calculated if the remaining miles is driven as the previous same number of miles were driven. As has been said = "There is a time to hold and a time to fold".

 

[MaverickDragon]

According to my 2025 searchable Owners Manual, it states fuel capacity as:
Hybrid Electric 13.8 US gallons (page 164. of 572)
All other variants 16.5 US gallons (page 165)
Slightly off topic bank, but I can recall when owner's manuals looked more like brochures than the current unabridged dictionary that is so large they don't even print it.
BOT
Regardless of the total amount of fuel that is begun with, no one ever had to schlep on foot to a gas station because they chose to get fuel when it was down to 1/4 tank.
OTOH, it is highly likely to find those that did just that, during a foray into the "we can make it there from here" mindset when the car decided to nap, as the formerly liquid environment the fuel pump was enjoying a bath in, became a sauna.

 

[Chops]

I would think the Hybrid Tank has a different shape & part# than the EB.
They have different components in different places down there underneath the truck.

 

[Chops]

1. The tank Actually holds more than 13.8. I actually ran mine to zero. It held about 14.5

The Hybrid has ~ 1 gallon non pump able reserve tank beyond the 13.8. Not sure what good a non pumpable reserve is?

Also, mpg plummets as you get low on fuel as the Hybrid will try to preserve the high voltage battery by using the ICE only…

 

[Darryl]

The Hybrid has ~ 1 gallon non pump able reserve tank beyond the 13.8. Not sure what good a non pumpable reserve is?

Also, mpg plummets as you get low on fuel as the Hybrid will try to preserve the high voltage battery by using the ICE only…

Well, if the tank held over 14 gallons, it evidently was pumpable . The the truth is that almost all fuel tanks hold more than advertised even if you stop at the first or second click during a fill-up. As for the plummeting fuel mileage, I believe it had more to do with the fact that the previous 100 miles consisted of the type of driving that was most advantageous to the hybrid city driving at or below 45 mph. Then I immediately went to driving at 75mph where it's virtually all ICE . I typically get 40+ under the first type of driving. I typically get about 32 at 75mph . So I should have anticipated it. I also noticed that DTE seems to drop more quickly for the last 20 miles for most vehicles I've owned. I think that's probably by design to make it drop to zero before it's actually empty. They try to anticipate idiot behavior like the kind I was guilty of

 

[MakinDoForNow]

According to my 2025 searchable Owners Manual, it states fuel capacity as:
Hybrid Electric 13.8 US gallons (page 164. of 572)
All other variants 16.5 US gallons (page 165)
Slightly off topic bank, but I can recall when owner's manuals looked more like brochures than the current unabridged dictionary that is so large they don't even print it.
BOT
Regardless of the total amount of fuel that is begun with, no one ever had to schlep on foot to a gas station because they chose to get fuel when it was down to 1/4 tank.
OTOH, it is highly likely to find those that did just that, during a foray into the "we can make it there from here" mindset when the car decided to nap, as the formerly liquid environment the fuel pump was enjoying a bath in, became a sauna.

Need to have at least 3 hours worth of extra idling AC time in August while traveling i40 across the desert in the west! Been there done the big wreck!!!!! In years past also stopped and bought a case of bottled water in 114°F heat for 1.50 a bottle. Wife and kids in car and just leaving town with sign that read "next gas and food 89 miles".

 

[Chops]

Well, if the tank held over 14 gallons, it evidently was pumpable

I think that's probably by design to make it drop to zero before it's actually empty. They try to anticipate idiot behavior like the kind I was guilty of

I can’t think of a better “idiot” to test that functionality than you

Now the genuine idiots like me won’t have to do the that experiment!

 

[Darryl]

I can’t think of a better “idiot” to test that functionality than you

Now the genuine idiots like me won’t have to do the that experiment!

I have been known to add being absent minded to the idiocy. I pulled the "I will buy gas in the morning" self deception wants with my old car. Of course I forgot and took off to work anyway. My car showed 0 to empty with about 15 miles left. No more gas stations before work. I made it to work. Left work and passed by two gas stations, headed to Walmart. Passed by the Walmart station leaving Walmart then remembered that I needed gas badly. At that moment I ran out of gas. Thankfully I was within walking distance of 3 gas stations. So I had to walk to home Depot, buy an overpriced I gallon cash can, walk to the station, walk back to my car and pour the gas in . It was over 90° at the time!

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