A bit TOO far into the reserve?
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Depends. There's typically room in the tank for another 3.5+ gallons (after the initial shutoff) if you pack it in. But you may compromise the vapor recovery system in so doing.
The most I ever packed in was just over 24 gallons... before I learned the error of my ways.
Looking over my records, I have 20 fillups with 22+ gallons which includes several 23+ gallon fillups and the one 24+ gallon fillup.
I have always wondered (given the various flow rates from different pumps) how close to the 22 gallon capacity we typically get when the fuel hose clicks off that first time.
The most I ever packed in was just over 24 gallons... before I learned the error of my ways.
Looking over my records, I have 20 fillups with 22+ gallons which includes several 23+ gallon fillups and the one 24+ gallon fillup.
I have always wondered (given the various flow rates from different pumps) how close to the 22 gallon capacity we typically get when the fuel hose clicks off that first time.
A logical conclusion, however, not supported by the facts. I was routinely getting upper 300's to 400+ miles to the tank than when filling normally.... an indication that I was actually getting the fuel the pump said I was getting.
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I was running a test using 87 octane nonEgas and concluded that my mpg was improved 1 to 1.5 mpg... but that the extra cost of the nonEgas negated any savings after a certain price point. I carefully trickle fueled each tank of gas using the same pump and the same orientation and filled to just below the brim each time. I was able to pack in another 3.5 gallons (+/-) each time. This was as controlled of a test as I knew how to do on my own.
I was running a test using 87 octane nonEgas and concluded that my mpg was improved 1 to 1.5 mpg... but that the extra cost of the nonEgas negated any savings after a certain price point. I carefully trickle fueled each tank of gas using the same pump and the same orientation and filled to just below the brim each time. I was able to pack in another 3.5 gallons (+/-) each time. This was as controlled of a test as I knew how to do on my own.
Hey Speed, looking at your chart, how long did your running average MPG continue to go up? Or did it make the turn down there at the end of the data?
My experience is similar with the 3-3.5 gallon bump by "topping off" the tank which is something they really do not want you to do.
Although it adds weight to the truck which would theoretically reduce the MPG, I do it mainly to add range...I hate standing at a gas pump when there are better things to do. I use the truck for work and work often requires me to drive well over 100 miles a day. I sat down and figured it out once a few years back and topping the tank was saving me something like 13 hours a year standing at a gas pump. Yeah, I know, totally anal.....
My experience is similar with the 3-3.5 gallon bump by "topping off" the tank which is something they really do not want you to do.
Although it adds weight to the truck which would theoretically reduce the MPG, I do it mainly to add range...I hate standing at a gas pump when there are better things to do. I use the truck for work and work often requires me to drive well over 100 miles a day. I sat down and figured it out once a few years back and topping the tank was saving me something like 13 hours a year standing at a gas pump. Yeah, I know, totally anal.....
It seemed to start falling off within a few tanks of 87 octane Egas. My rolling 10 tank average decreased over 1 mpg 4 months later. (I even tossed a tank of 93 octane in there). You can see where I quit packing the fuel in after 5/9.
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And here's the same time period a year later. Included in this time period, I ran a test of 89 octane for 9 tanks. I did not observe any benefit. Of course, different weather, different trip makeups... all come into play to affect mpgs. But still...
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And here's the same time period a year later. Included in this time period, I ran a test of 89 octane for 9 tanks. I did not observe any benefit. Of course, different weather, different trip makeups... all come into play to affect mpgs. But still...
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How are we compromising the vapor recovery system by topping off? How high should we go?
Technically, stop at the first click off of the pump. That being said, I've experienced no issues from topping off as much as I did. Yet.
Ditto this. I've been routinely topping for 10 years in a Ridgeline without a problem. When I say top, I mean I can see the gas in the filler neck just before it overflows.
Honda and all other manufacturers I know of say not to do this, and in fact it can be "illegal" in most areas due to the probability of gas fumes and even liquid gasoline escaping. The fill system is even designed to defeat topping by narrowing the filler neck above the gas tank. Some states require a fume recovery system on the pump hose as well.
YMMV
While I haven't experienced any issues yet, I think the proverbial YMMV is appropriate as a disclaimer. Still, I take the prospect and warnings of damage to the vapor recovery system seriously.
Personally, I would love to go back to filling to the brim. I enjoy those 400+ mlle tanks of gas. I have at least a 2 mile journey to the house from the closest gas station and park in a garage so am not concerned with heating and overflow issues.
Personally, I would love to go back to filling to the brim. I enjoy those 400+ mlle tanks of gas. I have at least a 2 mile journey to the house from the closest gas station and park in a garage so am not concerned with heating and overflow issues.
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11,315 Posts
Keep in mind, most people who top-off are not car nuts. They do it indiscriminately not paying that much attention to the actual rise in the filler tube and in addition are usually in a hurry.
The regs are really aimed at those folks.
Plus, no automaker in their right mind is going to have statements in their owner's manual that say "topping off is permitted as long as you are VERY careful!"
"If you drive very slow and are careful not to hit or be hit by anything, you don't need to wear seatbelts either!"...
The regs are really aimed at those folks.
Plus, no automaker in their right mind is going to have statements in their owner's manual that say "topping off is permitted as long as you are VERY careful!"
"If you drive very slow and are careful not to hit or be hit by anything, you don't need to wear seatbelts either!"...
That may well be true. However, the prospect of hidden damage to emission control components is daunting to the filler-upper.
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Yes, to those of us who are aware of such things. We are in the minority for sure.
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199 Posts
Heck, I thought I was some sort of refueling ninja when I saw that 22.0637 reading on the pump. Never imagined one could pack in 24 gallons, nor would I have a real reason to do so. I get the increased range, but it seems like I'd spend s much time trickle fueling my Ridgeline those last three or four gallons as I would just refueling soon after the low fuel light came on and getting back on the road.
Anyway, my primary objective is just NOT TO RUN OUT OF GAS! Now that I know there could be come possible damage or negative impact to the emission control system I have even less reason to top off the tank, even if it would be nice to once in a while get a 400 mile range out of a single fuel stop.
Roll On fellow ROC'ers...
Anyway, my primary objective is just NOT TO RUN OUT OF GAS! Now that I know there could be come possible damage or negative impact to the emission control system I have even less reason to top off the tank, even if it would be nice to once in a while get a 400 mile range out of a single fuel stop.
Roll On fellow ROC'ers...
The low fuel light is set to come on when there is approximately 3.3 US gallons left until the needle reaches the E... at which point a small (undefined) reserve remains. I guesstimate that when the light comes on I have about 4 gallons of fuel remaining.
So that is really your key to not running out of gas... not how much you pack in the tank!
One of the things I like to do is know how far I can reliably go after getting the LF light. There are simply times in life when a fuel stop is not in the cards right when the light comes on. I will go 40 to 50 miles on the LF light before getting antsy.
How far did you drive into the LF light on this occasion?
Edit: one caveat: some believe the fuel pump is cooled by immersion and can be damaged by running with low fuel. Personally, I think the fuel pump is cooled by the fuel flow, so I don't worry about the fuel pump and running the tank low. As usual, YMMV.
So that is really your key to not running out of gas... not how much you pack in the tank!
One of the things I like to do is know how far I can reliably go after getting the LF light. There are simply times in life when a fuel stop is not in the cards right when the light comes on. I will go 40 to 50 miles on the LF light before getting antsy.
How far did you drive into the LF light on this occasion?
Edit: one caveat: some believe the fuel pump is cooled by immersion and can be damaged by running with low fuel. Personally, I think the fuel pump is cooled by the fuel flow, so I don't worry about the fuel pump and running the tank low. As usual, YMMV.
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118 Posts
I'm too chicken to run my tank that low. I get all panicky once the light comes on, and I am obsessed with getting the tank filled ASAP. I know there is no justification for it, but I still get worried when the low fuel light comes on.
I can say that I have run over 400 miles on a tank before though. Going from Ohio to Chicago, I can get 22-23 MPG on the highway, once I clear Columbus. East of Columbus has all the hills, west is like Kansas.
Rob
I can say that I have run over 400 miles on a tank before though. Going from Ohio to Chicago, I can get 22-23 MPG on the highway, once I clear Columbus. East of Columbus has all the hills, west is like Kansas.
Rob
Those mpgs exist only in my dreams. I've never seen better than the mid 21s. Perhaps I've never driven in an environment that would yield those mpgs. Oh well.
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199 Posts
speed, I'd guess that I drove 60 miles after the low fuel light came on, no more than that anyway. I usually don't driver more than 30 miles or so once the light comes on and I usually don't get much more than a 20 gallon refill. Sort of makes sense I reckon. I don't think I'll make a habit out of running 60 miles after LF light :act002:
I have never seen 23 MPG either. I rarely get to drive flat highways and my cruise is set on 74 miles per hour when I'm not in the Winston city limits. I average right at 18 MPG in my mixed driving which is about 60/40 HWY/CITY. I rarely see a 400 mile tank, but for me refueling is never very inconvenient.
I have never seen 23 MPG either. I rarely get to drive flat highways and my cruise is set on 74 miles per hour when I'm not in the Winston city limits. I average right at 18 MPG in my mixed driving which is about 60/40 HWY/CITY. I rarely see a 400 mile tank, but for me refueling is never very inconvenient.
Yikes. 60 miles on the LF light would definitely raise my pucker factor.
Ah well, these discussions are always good for some entertaining commentary and anecdotes!
Ah well, these discussions are always good for some entertaining commentary and anecdotes!
Personally, I never let the tank get to the point where the low fuel light comes on. I've heard horror stories of the "sediment" in the bottom of the tank being sucked through the system and clogging up the filter and/or lines. On the other side, I've also heard that the evaporative emissions system (vapor recovery) can be damaged if you top off after the pump initially clicks off. So, I usually fill up when I have about 1/4 tank left and let it run until it shuts off. Whether you have 20 or 24 gallons in your tank, you're going to be driving the same distance no matter what. The only downside is that you fill up a day sooner. I have three gas stations that are on my 3 mile drive home from work, so it's never really an issue for me.
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