Fuel tank top off is bad. I'm now a believer.

well they did put the cutoff valve on there to help prevent overfills but if you really overdo it, it's useless.

there's also a check valve on there to keep minute amounts of fuel from entering the evap system but again, soak that sucker in fuel and there's not much it can do.

 

The system could have been designed to be both environmentally friendly AND difficult to damage by making it to be hard to damage during refueling. The Prius is not a Citation jet, a Boeing 737, or some type of machine that requires specific fueling procedures by trained personnel. I think Toyota's 'recommended' procedure that the fuel tank never be allowed to be topped off because it may damage the system is a design flaw. I have been driving automobiles for over 30 years and never once have I had an issue (or even heard of such a problem) with topping off the fuel tank during refueling.

And you also go on to say Toyota has designed an 'excellent fuel storage system'. Really? You must be new to this board. With the exception of discussions regarding fuel economy I would believe the shortcomings of the Prius's fuel system are discussed more than perhaps any other system on this automobile. Whether it be the finicky bladder, topping off, fuel gauge inaccuracies, etc.; they have all been discussed at length with every thread ending with the attitude that you must 'just live with it'.

You want to save the environment, well that's great. But if you do it at the expense of your customers then there won't be much to save will there?

I predict that future generations of the Pruis and perhaps other Toyota automobiles will have a fuel system that is still just as environmentally friendly as the present system AND difficult if not impossible to severely damage by the common practice of 'topping off' the tank. It is not that difficult to engineer such a system.

I have no clue what you are implying with the above...


Rick
#4 2006

 

along with idiot-proofing the fuel storage system, we can also prevent a drunk from ever driving another foot on our streets... its all a question of money.

in the drunk driving area, its a lot of money... retrofitting all the cars to detect alcohol levels of the driver is not advanced technology... but no one wants to pay for it and they use some lame assed excuse about personal rights as a smoke screen to effectively stall the technology from being put into place.

so how much money should Toyota spend to insure that a certain percentage of its customers will be able to get an additional 50 miles out of tankful of gas without risking a major repair bill?

thankfully not too much

 

Almost every new (ish) car that I have driven lately (and taken the time to read the manual) states the you should stop fueling when the pump clicks.

I just can't figure out why, unless you are driving across the outback somewhere where the next gas is 400miles away, people feel the need to add another litre or two to the tank? What real difference does it make? So you have to fuel 50 miles earlier whoopdee freaking doo! If I'm driving 'cross the great empty (which I do regularly) after 350-400miles someone needs to pee anyway, so why not stop and fill at the same time.

If your in town, so you fuel 15 times a year instead of 14! (or whatever) Seem the time saved by not topping off would equal the extra fill up!

Sometimes people are so strange!

Icarus

 

what some people simply dont realize is that the damage that can be caused by overfilling their Prius is pretty much the same as overfilling EVERY new car today because of changes in how fuel is stored as a result of stringent anti pollution laws today....

some people choose to continue topping off their tanks simply because they could do so in the past and get away with it.

just some will continue to not wear seat belts because up to now they have been able to get away with it.

 

This is where we differ, personal rights and governmental intrusions. Yes, I believe, for a person who has no record of DUI, it IS and WOULD BE a personal intrusion and insult to require me to blow into a tube EVERY time I start my automobile to determine whether or not I am intoxicated. For example, I don't ingest or deal with illegal narcotics, so why should I be afraid if a agent of the government shows up to my door on a random basis to conduct a search of my house or person for such contraband? After all, I have nothing to hide.

BUT, nonetheless, I along with the vast majority of citizens of the world would be greatly offended if agents of the government conducted random searches of my person or domicile WITHOUT probable cause. And for those of you who live outside of the United States, this is a right so treasured by Americans that it is a part of our Constitution. I don't find defending this right a 'lame nice person excuse' as you so state above. And, knowing your political leanings, I am truly surprised you would even suggest such an intrusion.

You still seem seemingly convinced that it would be too costly for Toyota to design a fuel system that is both environmentally friendly AND that would be difficult for the average consumer to overfill for a reasonable (or same) cost. I still disagree. Toyota can do better.

Is this a major problem with other cars? Are cars lined up in shops and dealerships with failed fuel evap systems because some poor bloke 'topped off' the tank? I doubt it. For Toyota to issue such a detailed report to techs dealing with overfills and the extremely costly repairs necessary (replacing the entire tank and other components!) indicates to me a design flaw.

Automobiles must be designed for nearly everyone who holds a driver license to operate in a safe and trouble free manner. And Toyota and other manufacturers do a pretty good job at that. However, I still find it unacceptable the Prius could sustain such severe and costly damage to the fuel system by simply topping off the tank.

Rick
#4 2006

 

any reputable company would issue reports detailing possible consequences if recommended guidelines arent followed.

i personally know two people who will spend an additional 5 minutes at the pump dribbling in a few more drops of gasoline... one of them drives the first 04 model Prius i had ever seen in person. he's got around 40,000 miles on his Pri and still no ill effects and he tops off every tank. i have only been with him maybe a half dozen times when he stopped to get gas and i saw him overfill and spill gas twice...granted that was in the early early days...

but are there cars in shops because they were overfilled? oh ya there is. i know a guy who had a car that needed its in tank fuel pump replaced and it was later found that it needed replacement because a vapor cannister that was never meant to get wet, was soaked in gasoline causing too much back pressure. and this happened YEARS ago... like 1998, 99 maybe and on a car that was 3-4 years old to boot

 

inside the PDF there is the explanation wy people have trouble with petrol coming out of the gas nozzle

there is a cuttoff valve to prvent overfilling ( page 9 )
zo you can not overfil your prius and if it dus then the cuttoff valve is nog working correcly and you need a replaced maybe onder warranty

 

I never top off my tank because of what I have read on this forum. But...in order for me to maintain that rule I cannot go to a "full service" gas station because they will regularly keep pumping after the first click in order to reach an even dollar amount. So what about people who would rather use the full service stations? What is their experience?

 

with an "even dollar" requiring less than a third of a gallon, you have nothing to worry about... in most cases, overfilling requires significantly more than a gallon after the first click off...actually closer to two

 

Fill 'er up, but don't top it

Here in Oregon, and the only other enlightened state, New Jersey, only trained professionals can fill your tank. I routinely tell them to fill the tank with regular but don't top it. Usually they listen. I agree with Dave that a little bit added after the automatic cutoff won't hurt.

It's great to not get gasoline on your hands when going to work or out to dinner.

 

Re: Fill 'er up, but don't top it

Hold it right there, New Jersey weighs in!

In my 31 years of driving I have never been a "topper offer." I also had a mini career as a gas station attendant in my distant youth. I was one of those extinct full service gas station attendants who would fill your tires with air, check your oil and other fluids (add as needed) and make all of your windows and exterior mirrors squeaky clean while putting gas in the tank. I did not grow up in this state where only allegedly trained professionals may pump gas. In NJ, "Full Service" means I am not allowed to pump my own gas. I would keel over dead if somebody cleaned the windshield. So here is where theory meets reality.

The nitwits who usually fill the vehicles of NJ are for some reason disposed to topping off. You have to instruct and then WATCH them to stop them doing it. Which pretty much defeats the purpose of not doing it myself. I have a theory on why they do it, based on my work history, but it does not flatter the attendants.

Making change for cash transactions is a problem for gas station attendants. So in days of yore, one would usually get pretty good at running the pump to an even dollar to facilitate making change. But somehow these folks failed to notice that a cash-paying gas customer is as rare as a bald eagle in central NJ. We hand over our credit cards and they get sucked into the machine (placed there by the attendant) who then proceeds to pump to the next round dollar amount as if making change is still a big concern.

Anyway, I am unconvinced that there is any kind of meaningful training, although no doubt they all have certificates from some "gas pumping training program" on file. The appearance of compliance is what its all about. Gee I sound cranky.

 

the topping issue can be fixed quite easily... get an EV... i "top off" every chance i get!!

 

Anyone reading this thread cannot help but be careful not to overfill your tank.

Last week I filled until the automatic shutoff on the pump nozzle activated, then filled it again and it activated almost immediately. I paid and drove away , all the time watching my fuel gauge waiting for it to move to the full position. We all know that it is slow to move. This time it did not.. the tank was only about five-eights full. Since I wanted a full tank for an upcoming long drive I returned to the gas station and refilled it the next day. I ended up filling very slowly for quite some time with many automatic shutoff clicks interrupting my fill. Finally when I drove away it was full, but at no time did any gas overflow or burst out of the filler.

I am in somewhat of a dilemma now. If I stop filling when the nozzle clicks off the tank will be only partly full, whereas if I dribble it in carefully I may end up overfilling and damage my charcoal filter. Has anyone else found this problem?

 

my last tank did the same thing... but i did not stop... i clunked in another 2½ gallons because i knew how far i had driven and i knew what the MFD said so i knew how much gas i could put in...

albeit, not to worried but to play it safe, i short filled it about ¼ to ½ gallon


ps...short distance on tank was because we were taking a trip to an area where gas averages 20-30 cents per gallon higher so filled up before we left although we probably could have made it there and back without the fillup

 

Methinks that might be a problem with the pump mechanism. If I have one that behaves that way, I move to another pump.

 

OK, I read the document from Toyota Technical Training. I read the procedure for refilling the tank (page 11 of 18). It says, "When refueling, the engine is OFF and the EVAP VSV is CLOSED (OFF)." But Toyota says "the engine is OFF," not the car is off. Page 1 states, "A bladder fuel tank is used to reduce fuel vapors when the vehicle is parked, during refueling or while driving."

So I am wondering specifically what valve is open that would be closed if the car was off.

It says the Purge cycle will only occur when the engine is running, so maybe if the engine was running and it was being refueled and at the same time it decided to do a Purge cycle something unusual could happen. But other than that, and if the engine is off, I can't see any difference between having the engine off and the car off, at least as relating to refueling.

 

I guess I'm doing everything wrong then and still haven't had a problem(14K+ mileage). I top off and I usually have the car in ready. What's the difference between that and a vehicle driving up next to the pump while you're filling up? Are they going to shut down gas station parking lots to all vehicle traffic while customers are refueling?

 

For the Prius to be ready to recieve fuel and all the vent and emission valves in the right place the system MUST NOT be in ready mode. It is also important to push the nozzle right in. If you do this the fuel goes in easier. It will be hard to fill in ready mode as the tank won't be able to vent to fill fully and it may force fuel through the carbon canister, very bad.

This applies to North American models, I know this and I live in Australia.

 

I am still looking for specific documentation which states what is different with respect to any "vent and emission valve," or anything else concerning the fuel system, between the READY mode (with ICE not running) and OFF.