Acurasnake

is it good to fill your gas tank all the way?

....until the gas spills over?

is it bad for the engine?

i heard from my friends that it's bad to do that.

does anybody know the reason behind this?

Bluenote

No, it's not good for the car. Specifically, the Evaporative system will become contaminated with liquid fuel, when it's supposed to have nothing in it besides fumes. This could cause MIL after MIL. Once this contamination occurs, it is very difficult to remove, especially since repairs are usually done piece by piece, the ECM reset, test driven, etc.

Don't top off!

spooky3ce

Actually... ... don't top off... but there is an exception... i worked at Chevron for a year... to pay for my books for college, its a diffrent story... anyways, everytime i was to fill it up... i'd leave the pump running and once the pump clicked off i always gave it one more push until it clicked off... this is a good idea because some cars, not all, tend to click the pump off once to much vapor enters the pump... So, its not generally topping off its just double checking that you did get a full tank of gas...

Story time:
I was at some random gasoline station... Beacon i think owned it... anyways i always leave the pump so it clicks itself off... so i did just that it clicked itself off at about 7. something gallons and i as like that didn't take much... so i took the pump off etc... when i started my car the needle went up slowly... i was like if i drive around it'll get to where its going to get... me thinking right on the F for FULL... nope... it stopped about a little over 1/2 a tank... so its not bad to double check and push the pump one more time... it doesn't top it off until it'll actually spill...

lol... in conclusion... sound like i'm writing an essay... i think its not to bad if you accidently top it off once probably every 2 week or once a month...

Answer to your question is basicly the post above this...

WolfpackBill

You're right! My Explorer has a long fuel tube down to the tank. It's also fairly narrow and it's also located at the back of the tank. Anyways, I can always fill up a couple more gallons after the first click. Why do I do that, you ask? My Explorer has a trip computer that shows many neat things such as how many gallons of gas I've used, distance to empty, when to change oil, light checks, oil pressure test, etc... So I just follow whatever was shown on the computer and fill up according to that. The computer would show that it used say 18.5 gallons, then I fill up and the first click would be at 16.7 gallons. Well, I can literally fill up to 19 gallons without actually topping it off. Oh yeah...with my truck, I can actually fill more gas facing a down slope. It's awesome!!

So in conclusion, topping it off is bad, but like what Spooky said, it's not really a big deal if you've only done it once or twice.

wackjum

Gasoline pumps don't smell the vapor or anything to know when to cut off.

Near the tip of the nozzle is a small hole. This hole sucks in air as the pump is filling. The idea is when gasoline has come up high enough, the hole will suck in gasoline instead of air. It's harder to suck up a liquid than to suck up air, so the pump knows to stop.

This also means that anything that affects the rate of air going through that hole will trip the automatic shut off. If you have a narrow tube like WolfPack is saying, it is possible that a mini vacuum is being created in that fueling tube since the air in the tank is so far away, and then that will trip the automatic shut off.


As for Acurasnake's question: Yes it is bad to do that for the reason Bluenote said (tighten the gas cap 3 clicks!). But also because spilt fuel causes pollution.

Acurasnake

thanks guys!!

man i really love this forum!!

HQuakers

On a side note, I was filling up yesterday and some white trash douchebag tapped my bumper when he pulled into the pump. There wasn't any damage, not that I really care because it's already dented.

Ken1997TL

Yeah, don't put too much in there. If you just do once quick squeeze to get your gas bill to an even number you should be ok.

Just don't force it and you'll be fine

longeye23s

its also not good to always be on empty. always full ur tl when its about 3 quarters empty. theirs dirt that is left in the bottom of the tank..

Ken1997TL

In addition, the fuel pump has to work harder.

wackjum

And in a lot of modern cars, the fuel pump is cooled by the surrounding gasoline. Running on empty could overheat the fuel pump.

Finally, in the winter for cold climate people, keep your tank more filled than you would in the summer. Water condensation could form in the tank and drop to the bottom of the tank (since water is heavier than gasoline) and rust the fuel tank out. Condensation can't form if the tank is full.

ELA.TL

dammmm.... i always let my car go to E (empty) then run it about another 15 miles afterwards...... Im just like that.. oh well i guess being stranded 3 times with no gas has yet too teach me the lesson i deserve..

Worst case was going south on Las Virgenes Road (ventura) all canyons, very hilly....lol really dark on a two way highway went there not knowing how far it was and having my company car on E... i was shitting brics on the way up, turning the radio down, making sure the car did not know it was running out of gas. I barely made it.. but i was sweating it..

in conclusion.. do what he said.. fill up at 1/4 tank...LOL

spooky3ce

I let it go down as far as the E but never ever let it go too far that the fuel light comes on to remind me... Does anyone know about the little light??? because on my moms Accord, everytime my mom would let it remind her to fuel up and now when you let it go down to a little less then a quarter the light comes on instead of waiting for it to reach the E... Would the ECU be switching it on because she has let it go down so much... Thats the main reason i don't let it go down all the way in my TL because i don't want it to remind me when its only 1/4 full...

Cornflake

I usually fill up at the light, I'm just lazy to go tot the pumps, and with the price, I try to push it if the price s high when I'm low, by the same token, I top off if I am anywhere less than 3/4 full if the price is down...well any ways, I ran out once last winter, froze my ARSE off waiting for my slow ass brother to pick me up and go get a jerry can!!! Lesson learned, now I don't let it go below 1/4 in the winter.....!!!! As for topping up...Wackjum is right, the pumps only shut uoff when the gass hits the nozzle or at les if the vacuum created cause it to THINK the tank is full. Also some cars the filler tube causes liquid gas to spray back onto the nozzle and it thinks the tank is full, you actually have to position the nozzle at a certain angle even when the tank is empty. In the TL this isn't a problem and I usually just top off to the next buck when I'm filling up. It is best for the environment NOT to overfill, but a small drizzle will evapourate before it hits te ground anyways as it runs down the overfill in the fuel door.

fla-tls

Ummm... The fuel pump ALWAYS picks up from the bottom of the tank. If it didn't you'd run out at half a tank.

This is an urban myth that needs to die!

I always love the "there's water down there - so don't let it get too empty and cause fuel line freeze in the winter" posts.....

WBroylesH

I didn't know the fuel pump was cooled by gasoline. That's an interesting fact.

I've heard it's ineffecient to top off particularly in hot weather because the top gasoline evaporates before it can get used.

vanz

I just pump until it clicks off...

but now, since I live in oregon, I don't pump my own gas anymore.