Auto-shutoff not filling the fuel tank?

[BlacknTan]

Two things:
1. You can drive 5-6 hours before you have to stop to fill up? You can go that long without peeing or stretching?
2. You drive until your tank is down to two gallons?

I can just do six hours on a full tank, and I can do ten hours without peeing .... I do it every night in bed! :thumb3:

 

[2014 Warthog]

Thanks for this. You provide a plausible answer for one of those nagging questions that kept puzzling me - why I am never able to add more than 20 gallons in the tank - even when filling from bone dry empty.

It's a bit disingenuous from Toyota though - calling it a 23 gallon tank when only about 20 are usable - although I suspect all the manufacturers do the same.

The takeaway here is that the tank is never completely full. Which is a safer place to operate from than assuming you have a couple of gallons below the empty line on the gauge.

Er...

All 23 gallons are usable. When the gas light comes on it's at about 20 gallons to refill leaving three real gallons of gas left in the tank. You can use as much or all of it as you want

In fact, given the expansion space, the tank may actually hold 25 gallons completely up to the neck!

 

[Blitzkrieg]

I find this thread bizarre.

So we are talking about risking overloading your evap system because you want to fill the tank until it's basically running out of the filler. I got that right?

Let's do some simple math and round for simplicity.

You fill 20 gallons and it's running out the filler neck

You fill 18 gallons and the auto shut-off says time to stop.

You go drive a bunch and get to 1/4 tank on the gauge. Do you frequently say "I got 43 miles left before this baby is running on vapors" and do that or do you say "It's got a quarter tank and I need to fill"?

The simple math I am talking about is you get XX MPG. Whether you run it dry and overfill it or fill it with a half tank or quarter tank you still are using the same amount of fuel. I cannot think of any trip in the continental USA where this is an issue. I occasionally drive in very bad weather. One thing you learn here is never, ever let your tank get below 1/4 full. That 1/4 tank might be what keeps you alive if you get stranded.

I might be missing something here, but this sounds like a huge non-issue to me.

 

[FrontRange4Runner]

For me it's pretty simple....
1. Fill tank on the slowest setting the pump offers. Less fuel going in allows more time from air and vapors to escape. This means less back pressure and less premature fuel shutoffs.
2. When the pump clicks off, I am done. Continue on your way thinking about more pleasant things, such as how much less it just cost to fill the tank, vs. last year at this time.

 

[Friggin Idiot]

I cannot think of any trip in the continental USA where this is an issue. I occasionally drive in very bad weather. One thing you learn here is never, ever let your tank get below 1/4 full. That 1/4 tank might be what keeps you alive if you get stranded.

I might be missing something here, but this sounds like a huge non-issue to me.

I posted the revisit because of a request to see how things went in warmer weather. Top off or not is up to you. The discussion was started because I noticed sometimes topping off the tank meant an extra .2 gallons and sometimes meant 2.0 gallons. That's a huge difference and I wanted to know if it was just me.

Today those 2 gallons made a difference between stopping near my house and my preferred 100% gasoline Sinclair station, or stopping 50 miles short of home to toss in a few more gallons of 10% ethanol poison (at a higher price) to get me to my preferred station. That's a minimum of 10 minutes saved by taking the 1 to top off the 2 extra gallons at the previous stop. It doesn't usually work out this way, but I had the usual travel snafu's: sitting idling on interstates, unexpected headwinds, and every red light you can get from highway speed (US/State Routes).

Is it required to fill those last 2 gallons, certainly not. But why stop more often for fuel if you don't need too? The 4Runner can burn fuel faster than it can expand. As long as you're consuming about a gallon of fuel before stopping, you should never worry about your evap canister.

It was 85-95F and partly cloudy along my whole route today, so I seriously doubt running below a 1/4 tank was a life or death matter. In winter, unknown/unfamiliar or wilderness areas that is a very different story. Would you worry about running below a 1/4 tank while running errands around the city of Denver, or would you let it go until your errands are done and fill up on your way out of town? Consider the road ways you drive: back country trails or traversing sparsely populated areas at night below a 1/4 tank are a rule breaker, the interstates in the central US during weekday daylight travel not so much.

Is this really an issue, in the big scheme of life, certainly not. We each drive and care for our 4Runner in our own way. This forum is a great exchange of information, useful and worthless alike. If you have something to contribute please feel free, but if not may I suggest this thread.

 

[NYRunner]

Speaking strictly from hypothesis- isn't it possible that because of the shape of the gas tank and the intended use of this vehicle that the engineers wanted an extra few gallons in the tank at all times to keep the fuel pump from burning out or the vehicle from stalling when off-roading or wheeling at extreme angles etc?

Or am I speaking out of my arse?

 

[Friggin Idiot]

Speaking strictly from hypothesis- isn't it possible that because of the shape of the gas tank and the intended use of this vehicle that the engineers wanted an extra few gallons in the tank at all times to keep the fuel pump from burning out or the vehicle from stalling when off-roading or wheeling at extreme angles etc?

Or am I speaking out of my arse?

You're talking about what's called unusable fuel. This is the fuel left in the bottom of the tank that the pump can't reach or scavenge. Theoretically it would be possible to orient the vehicle in such a manner to make it usable, however, you would then have to idle in that orientation in order to make use of it. Having used that fuel, you would then have to add that amount back in at the pump. By comparison with airplanes which may have a few gallons unusable fuel, I seriously doubt that the 4Runner has more than 1/2 gallon unusable. Also remember multiple users report being able to get those extra couple of gallons at the pump regardless of previous tank level (empty, 1/4, etc.) So the unusable fuel wouldn't be a factor here.

I think the front end low really just lets the fuel tank vent better allowing air at the top of the tank to escape displacing that amount of air with fuel. If fuel pumps didn't have the pressure system of the vapor recovery and it was possible to overfill the tank onto the ground like days of old then we would be able to slowly displace the air at the chance of spilling fuel. So really it's as much to do with the addition of the vapor recovery pressure feedback loop as it is with the design of the tank.

 

[TheWraith]

All this talk about fuel and mileage. I wonder if there was a extended fuel tank upgrade out there for us. I know the Tacoma is a very close resemblance to our tanks. And there is a 32 gallon extended range tank from LRA out of Australia.

 

[Blitzkrieg]

Is this really an issue, in the big scheme of life, certainly not. We each drive and care for our 4Runner in our own way. This forum is a great exchange of information, useful and worthless alike. If you have something to contribute please feel free, but if not may I suggest this thread.

Easy there cowboy,don't get your panties all wadded up.

I was merely trying to figure out from the various posts in this thread if the common idea was variance in when a shutoff occurs or if it's prudent to bypass the auto shutoff and fill the tank to the gills (it's not).

What you didn't mention is if you are using the exact same pump at the exact same station to see this difference. If you aren't, it's a moot point because I guarantee you every pump is going to shut off slightly different. Wear, different style nozzle, whatever. Ever tried to fill at a station and the nozzle shuts off every 20 seconds and it takes you 10 minutes to fill? Thats a worn nozzle to the extreme.

 

[nglayton]

All this talk about fuel and mileage. I wonder if there was a extended fuel tank upgrade out there for us. I know the Tacoma is a very close resemblance to our tanks. And there is a 32 gallon extended range tank from LRA out of Australia.

I'm in for a tank upgrade. I've been looking for 3+ years for an easy, someone else did it first type solution. But I haven't found one.....So I'm all ears if someone knows of any!

 

[Friggin Idiot]

What you didn't mention is if you are using the exact same pump at the exact same station to see this difference. If you aren't, it's a moot point because I guarantee you every pump is going to shut off slightly different. Wear, different style nozzle, whatever. Ever tried to fill at a station and the nozzle shuts off every 20 seconds and it takes you 10 minutes to fill? Thats a worn nozzle to the extreme.

I thought I mentioned that in the OP, I've had it happen at several different pumps and stations. Being as other users not local to me have reported similar results, I'm inclined to think it's not the pumps. The amount that is used for the top-off does vary between pumps, but the variance as long as the front end is low is .3 gallons max (1.7-2.0 gal). While I do tend to favor one of the only two pumps at my favorite station, I can reliably reproduce it at other pumps & stations.

 

[Blitzkrieg]

I thought I mentioned that in the OP, I've had it happen at several different pumps and stations. Being as other users not local to me have reported similar results, I'm inclined to think it's not the pumps. The amount that is used for the top-off does vary between pumps, but the variance as long as the front end is low is .3 gallons max (1.7-2.0 gal). While I do tend to favor one of the only two pumps at my favorite station, I can reliably reproduce it at other pumps & stations.

I apologize then. I must have skimmed over and missed some stuff.

I didn't mean to raise a ruckus.

 

[Ron4RNevada]

Hmmm- Just gotta respond

Having read this and the other similar thread I've got a couple of comments:

1. I don't know of a single gas station anywhere in Nevada that you can pump gas "nose up", "nose down" or "sideways". Probably a law that says gas stations have to have level ramps.

2. I always set the nozzle flow speed on low. That gives me plenty of time to give the windshield a good was job'

3. I never top off.

4. I generally refill at about 1/8 to 1/4 left on the gage.

5. Doing mostly highway driving on a tank I average about 20mpg. That gets me around 400 miles to 1/8 tank.

6. Off road in 4Low I generally get between 10 and 13mpg. That gets me over 200 miles tom the tank.

7. Off roading with a mix of high range and low range I'm good for about 300 miles. If I'm planning to go more than 200 miles with a lot of low range I add my two jerry cans for an extra 150 to 200 miles. My jerry cans are the old fashioned kind -> made of steel with neoprene sealed steel bung (Not Democratic Socialist Republic of California Approved).

8. Around where I live the distance between most towns can be 100 miles or so - and in the boonies no gas at all, so I'm very aware of how much gas I have and how far I can go - - - -


The stock SR5 has an almost perfectly sized tank and fuel range for my needs.

 

[Blitzkrieg]

I'm going to reply to the other thread thats active to consolidate but I just read something interesting related to modern fuel pumps.

http://www.toyota-4runner.org/5th-gen-t4rs/228768-pumping-gas-slowly-nets-3-4-gallons-more.html