Very good to know.
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Stop When the Gas Nozzle Shuts Off
- Thread starter Unclebob
- Start date
Make sense. What I do once it clicks I pull the nozzle up and top it off that way. I just like to have it filled up to the top.
When the nozzle clicks off, the tank actually is filled to the top. When you pull the nozzle out a bit and add more, all you're doing is filling up the vapor hose, not the tank. You know it's not just the one filler hose there, right?
Here's what's on the other side of the filler door...
That little hose on top is the vapor hose, and when you top off the tank, especially if you pull the nozzle out a bit to do it, that's where the fuel goes. And the vapor hose doesn't lead to the tank, it goes to the carbon canister and EVAP system that's designed specifically to keep liquid fuel out. But overfiling the tank forces liquid fuel in there, anyway.
Setting aside the fact that liquid fuel damages the carbon canister, it takes days for the liquid to evaporate from the canister, and in the meantime the vapors from the tank have no where to go but to be vented out of the tank via the fuel overflow, along with the fuel which has expanded due to being hot because the cannister can't accept the vapors when the fuel expands. It's gotta go somewhere.
So every ounce you add to "top off" the tank gets vented and dumped, never burned in the engine. It's literally the same thing as trying to put 5.5 gallons into a 5 gallon bucket.
neilblack
Rookie Expediter
I would point out that copper is a great conductor of electricity and why is it showing up the diagramWhen the nozzle clicks off, the tank actually is filled to the top. When you pull the nozzle out a bit and add more, all you're doing is filling up the vapor hose, not the tank. You know it's not just the one filler hose there, right?
Here's what's on the other side of the filler door...
That little hose on top is the vapor hose, and when you top off the tank, especially if you pull the nozzle out a bit to do it, that's where the fuel goes. And the vapor hose doesn't lead to the tank, it goes to the carbon canister and EVAP system that's designed specifically to keep liquid fuel out. But overfiling the tank forces liquid fuel in there, anyway.
Setting aside the fact that liquid fuel damages the carbon canister, it takes days for the liquid to evaporate from the canister, and in the meantime the vapors from the tank have no where to go but to be vented out of the tank via the fuel overflow, along with the fuel which has expanded due to being hot because the cannister can't accept the vapors when the fuel expands. It's gotta go somewhere.
So every ounce you add to "top off" the tank gets vented and dumped, never burned in the engine. It's literally the same thing as trying to put 5.5 gallons into a 5 gallon bucket.
When the pump clicks off I leave the nozzle fully in the filler. I give it one more go which is usually 0.2-0.3 gallons. When the nozzle is pumping full flow I presume there is a bit of air as well as push back. I figure the extra quart of so fully fills the tank where the high pressure caused enough disruption to not do so. I'd never pull the nozzle out part way and top off nor would I give it more than one extra splash. I know about the overflow and it's possible I am shooting myself in the foot but I doubt it with just an extra quart or so. And yes, it's "only" a quart but that's about 15 extra miles.
tknight
Veteran Expediter
Technicality! Ok I get an extra 12 hrs of warm sleep from my new Espar!
Generally, only chronic overfillers who are ocd about filling to full dollar amounts run into evap problems.
When I have an audience, I'll put an even dollar amount in, then give it an extra 37 cents worth just to watch 'em squirm.
When I have an audience, I'll put an even dollar amount in, then give it an extra 37 cents worth just to watch 'em squirm.
I agree with Leo. When the pump clicks off I'm usually still cleaning glass or chipping ice off the washer/squeegee thing. All the gas and fumes have settled and I round up to the dollar. Yeah, I'm OCD about the even dollar. It makes bookkeeping easier. Although, with gasoline being under $2.00/gallon, I can't always round up to the next dollar.
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If that's the case, then the poor slob that bought my old van with 820,000 miles is probably out buying a new carbon canister as I type because the one in that van is the original.
When the the pump clicks off I'm done because I've usually been standing there doing a dance because I had to pee when I first pulled up to the pump.
They key to that is leaving the nozzle fully in the filler. The filler hose works just like a funnel, where you can fill the funnel up and then you have to wait for it to drain. Once the hose drains you can add a little bit more. But if you pull the nozzle out part way, the fuel just goes into the vapor hose. Most of it, anyway.
I used to be, but after I learned how the shutoff on the nozzle handle works I stopped.
It probably does need replacing. And they can be expensive. But mainly it's just a bunch of EPA crap.
It's both OCD, and skill.Is this OCD? I round up to the next nickel after the first shutoff