Filling It Up

So maybe I'm wrong but I thought I'd get other's opinion on this subject:

Whenever I fill my truck up, I take the time to fill it all the way up, that is, I fill the tank all the way up to the top of the tank, and up the tank fill spout, so that I can see the fuel, almost to the point of where it is spilling out of the fuel filler opening. I'm guessing that the gas station's nozzle shut off when the fuel backs up enough to activate a nozzle sensor to stop the flow of fuel? And that is probably when the tank is full at approximately 26 gallons. I then top it off by carefully squeezing the pump/nozzle (generally it takes a few minutes) over and over until I can see the fuel.

I've been watching the gas station pump and I'm guessing I can add an additional 2 gallons or so by doing this? I'm I wrong, is this not actually getting me any extra fuel? Thanks for your input.

 

Really surprised you can actually get an additional 2 gallons after the cut-off. Actually doubting extra 2 gallons but do not want to argue.

Any amount you get in there is usable fuel. Also thinking for safety reasons there may be a designed amount of vapor space in the tank that is being displaced by doing this. Then again I may have dreamed this and be full of sh!t. LOL

 

You might get more fuel in but run the risk of damage to the vapor canister which is difficult and costly to repair

 

Vapor canister, can someone please elaborate?

 

Probably not a good idea to top off given the range these have.

 

They have an Evaporative system of sorts

 

Save some cash for clearing codes and replacing the Vapor Canister. You may as well just leave it running while you're over-filling it too!

 

One more reason I've been doing this type of fuel up is because I want an accurate analysis of how good of fuel mileage I'm getting with my Fuelly app. I've been consistently doing this sense I've owned the truck but I'll stop if this is harmful to the vapor canister?

My average MPG is 14.8 driving primarily in the city but also some highway miles, with 91 octane and up to 10% ethanol

 

The shutoff is designed that way for a reason. The tank is pressurized as part of the evap system. I would not squeeze more fuel in after the shutoff has engaged.

 

Am I overfilling it, is this damaging to the truck? No codes are being thrown

 

good to know, thanks

 

Not to appeal to any paranoid tendencies, but you do know that all gas pumps have HC vacuum recovery systems that suck up the vapors to reduce air pollution, right? The vacuum hose is coaxial with the fill hose. Get your ear down close to your fill port...you can hear the sucking noise.

I've always wondered that if you top off, doesn't the vacuum system begin to suck up any over-filled liquid gasoline too? Is the result never getting completely "full" if the fill hose is sucking off the overfill?

What's a self-respecting paranoid to do?: Unclench and put up the filler hose when the auto shut-off nozzle says it's time.

 

Interesting, thanks

 

Give it a try, I'd love another person's opinion on this, thanks!

 

Not knowing how the Fuelly App works; do know the MPG = miles / gallons on paper. Does Fuelly need Gallons inputed? For consistency one can try to fill up at same place and stop at one or two clicks.

 

Yes you enter gallons, for example, a number like 17.563. I'm averaging around 18 gallons per fuel up, give or take. Again, I'm trying like crazy to be as consistent as possible on my fuel ups--same gas station, same general time I fuel up (around a 1/4 tank left) and same gas. Over and over.

My average MPG is 14.8
Last MPG was 15.3
Best MPG was 16.7

I also try to keep my tire pressure consistent. I'm guessing I can stop doing all this (filling it all the way up, same station/gas etc.,) because I have an accurate estimate of my exact mileage over the last year or so...

 

when you fill the fuel up that much, it goes to the charcoal canister and will eventually fill the canister which is not made for liquids, just vapors with minute fluid. can cause your rig to run like crap until vacuumed or replaced. figure about $350 for the canister alone.

 

Thanks a lot for this info, I did not know this!

 

I'm pretty sure people buy 5.7 Tundra's because they run great for a long time not for their MPG's. Letting the nozzle shut off will tell you about as much as crowding every ounce of fuel you can get in it will. You just have to do the same thing every time you fuel. Try taking a 4 tank average when your running in the same circles.

 

I did a firmware update on my 2015 and my low fuel light comes on when I’ve use 20 gallons. Before it would kick on and all I Would fill it with was 18 gallons.

 

Just and update on my Fuelly app information. I did not fill the truck up all the way to the top like before. All of a sudden my Fuelly app says my MPG is 18.6.

18.6 MPG

This must be an anomaly due to the fact that I'm not putting like, 2-3 more gallons in the tank like before?

 

There are so many variables from tank to tank, day to day, even hour to hour. The best thing you can do is to not reset the computer for about 1,000 miles. That’ll give you an estimate of the mileage “you” are getting in your conditions.

 

I've eliminated variables, per my posts above

 

You can’t eliminate the variables, you can’t even hold the variables you know of constant from day to day much less considered all the little things you can’t control (wind, how long you stop at red lights, elevation changes in different trips, etc, etc, etc). There’s no perfect way to do what you’re trying to do. The best way is to average your mileage out over 1,000 miles or something of your real world driving. But then you’ll have to do it in the spring, summer and fall too for seasonal averages. Or if you want to be that accurate, from individual trip to individual trip. Either way, the MPG blows on the Tundras. But they’re fun to drive. Lol

 

Not worth the minimal benefits; and if you do damage the charcoal canister it's about $296.00, which would ruin your MPG. The best way to get great MPG in a Tundra is to drive a Prius.

FYI - A quick search will show many articles as to why not, but here's a decent article on this from CNET - https://www.cnet.com/roadshow/news/overfilling-gas-tank-topping-off-dangers/

"You might damage your car: All US market cars sold since 1971 have a closed circuit system to trap and later burn the fumes from their gas tanks. A complex array of charcoal canisters, tubes, valves and sensors comprise a system designed to handle gasoline vapors only, not liquid fuel. Jamming too much fuel into it repeatedly can result in a Check Engine state that will keep your car from passing an emissions test and could cost hundreds of dollars or more to repair. "