Haha ! I was scared too !!

I get anbout 18 mpg, so 3.5 gallons would give me about 60 miles.

So I guess I had about 1 gallon left when I added the 2.5 gal jerry can - the needle didn't seem to move from E and the light was still on.

Bottomline is that the "idiot light" is there for several reasons and is not an Exact science. It comes on based on your cumulative mpg for your style of driving. People complain about it coming and it isn't "empty". Imagine riding on a trail that and tha trail is 30 miles from your main road and another 20 from a gas station. Would you rather know you have a safety margin for a safe return or simply run out within a mile or two if it coming on?

As for the fuel gauge... it is not an exact indicator but rather for general purpose info. In my previous JKU I was climbing some long ass hills on I-70 in Colorado and my needle buried itself, when I came out the other side, idiot light turned off. It was solely based on low fuel, but pump location within the fuel cell.

Thanks for that explanation. Most drivers have little knowledge of the fuel system and sometimes refer to old automotive hearsay. Can you clear up some of these?
1. Will any damage occur if the engine runs out of gas while driving at highway speed?
2. Will the fuel pump overheat and be destroyed?
3. Will water from the bottom of the tank get sucked up into the engine and damage it?
4. Will sludge/rust from the bottom of the tank get drawn up and clog the fuel filter?

Thanks.

Last week, I had driven my 4Runner to 1 mile to empty. I was already headed to the gas station so I wasn’t concerned. The low fuel light came on around 20 miles to empty. Topped it off at around 20.5 gallons. $106 dollars lol


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Tune in to "Coast to coast AM" Usually in the middle of the night.
Thay will have "mysteries of T4R fuel tank" program right after crop circles segment...

-Not really. Modern computer controlled engines are pretty good at protecting themselves to a rather decent degree, usually when you're running low on fuel the pump will start "sputtering" which will start to kill the fuel pressure and the engine usually just starts running rough, misfiring, and then just turning off. When we do EFI services where we hook up a pressurized can of cleaner to then engine, sometimes we don't get to the ignition by the time the vehicle starts sputtering and it'll just die. Hasn't harmed anything made in the last two or three decades as far as I've seen.

-If you mean "will the fuel pump overheat and be destroyed- IF the fuel level is run too low?" The answer is "it is possible." Modern (anything made from like the early 2000's up) Toyotas use a fuel pump housing to sit the fuel pump in as well as the fuel level sender; it's designed to hold fuel in a "reservoir" that the fuel pump physically sits in. (looks like the attached picture, though this picture doesn't show the filter sock. It's a wide, flat sock that mounts to that hose fitting by the fuel level float.) As you can see the housing is like a big cup, that "cup" will hold a decent amount of fuel that gets circulated into the engine when the fuel level is low. This is specifically to keep the pump as cool as possible at all fuel levels, even with say a cup or so of fuel in that "reservoir" it would take a lot of heat and time to get the liquid fuel and plastic housing to get hot enough to thermally degrade the pump in any significant manner before you ran out of fuel and the engine shut off. Now I don't have any real evidence for that opinion, I haven't tried to measure those things; instinctually once you see and understand how it fits in the tank and works, as well as understanding how fluid pumps work, it just becomes sort of intuitive that it is designed to prevent that.

-Yeah, sure. You would have to have a significant amount of water in your fuel tank and have that tank sit for a while for all the fuel to separate to have standing water in the fuel that could hydro-lock an engine. Though once it's been agitated some, that emulsion of fuel and water would make it's way into the engine which could cause issues after a long time.

-Rust? Only if you have a vehicle with a steel tank whose resin/plastic coating has failed. Sludge and debris? Yeah, it's entirely possible as that's why you have a fuel filter sock on the inlet of the fuel pump. Once you're driving and sloshing fuel around in the tank, it'll get that debris floating around and it could get sucked into the filter. But keep in mind that in tank pumps have a large, flat, rectangular fuel sock filter. It allows the filter to get fairly dirty before it starts affecting flow requirements of the pump. Most fuel tanks I've pulled (quiet a few going over 100k when we get some vehicles for the fuel pump recall) the amount of sediment that settles at the bottle of the tank is barely enough to fill up a tablespoon. I do suppose though in other places in the country the fuel quality may not be as good and you can get a lot of stuff in the tank, but I honestly haven't seen it personally.

Hope that answers things for you?

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Thanks for the explanation, @BlackWorksInc . That’s great information.

Light comes on when I have about 3 gallons left. So that would be about 30-50mi. I have only run it down to about a gallon of gas once or twice.

Many procedures for high pressure fuel systems actually recommend pulling the fuel pump fuse/plug and running the engine till it dies. This is to dissipate any high pressure in the fuel lines. It won't cause damage to the engine.

I’ve filled up with the gas light on 29 times. 17 times I’ve put back in over 20 gallons. 2 of those 17 times I put in barely over 21 gallons. I try not to push it past 30 miles after the light come on.
Oh, the last fill-up was the first time I’ve paid more than $100. Up until then, my most expensive was $81.

I was at work balancing my tires and got roped into helpin' the weekend crew with a Tacoma 20TA02 and 21TD03 recall because they were backed up. Took a few pictures of the assembly in various states of disassembly for you guys. This is roughly what they all look like, this one is a returnless system, but beyond that the overall concept is the same.

As you can see there's multiple chambers that fuel is cycled through to keep the whole thing relatively submerged even if the fuel level is low.

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Don't know if it's the same with submerged fuel pumps, but might also a good way to clog the pump's filter by sucking up any sediment that might have made its way into your gas tank. I used to run out of gas when I was in college on a semi regular basis. I eventually had to drop the gas tank and pull the fuel pick-up out to clean it off, all kinds of crap stuck to the screen.