Filling Prius gas tank

Don't be confused. The gas filling is a real pain until you start venting. The pip meter is just not that accurate and it takes a while to get the gas filling routine under control if your new to the car. Forget about how many gallons you think it should hold.
You will not outsmart this gas tank.
Get a routine going and the car will tell you what it likes.

I swear if you follow my advice and fill up every time it hits 2 pips you will get 8 gallons every time.

Fill the tank at 2 pips if your new to the car. Do not worry about how low you can get the gas tank to go because if you run out of gas in this car its a real hassle. Do not run out of gas in this car. It can get expensive.

Do not top off the tank. Do not understand why thats so ingrained in Americans but it is. I was the same way and it took time to change. Maybe because years ago there were not that many gas stations around and then cars got 15 miles to the gallon. This car gets 3 times that many miles and there's a gas station every 2 blocks.
So many posts here in the last 5 years about contaminated tank bladders from gas overflow. You'll know about it as it will throw a check engine light if it happens.

Go to gas station. Remove cap. Either go inside or open hood and check oil venting tank at least 1 minute. Fill up on slowest fill setting on pump. That's important too. At 2 pips showing it will shut off around 8 gallons. If not it will the next time. At 2 pips and first shut off you should show full tank and your probably good to the next 2 pips at about 375 miles.

Been doing this for 4 years. Not one episode at any station. Again it exacerbates filling if you let the tank go close to empty.

Good Luck!

 

I completely agree about the venting. If I get in a hurry, and don't vent the system like I described in my earlier post and/or fill the tank with anything but the slowest setting I either don't get a full tank (guess gage drop's two pips in less than 50 miles) or I won't get the expected range for the tank.

Bottom line. Vent the system before you fill, and fill at the slowest setting. When the pump kicks off, hang it up and pay. Next time the gage starts getting down towards two (2) pips, buy more gas.

 

Exactly. You really have to change your mind set dealing with this tank. Patience and no top off. But venting and slow pump only adds 5 extra minutes to your gas refill. I use that time to check the oil.

Toyota went overboard with vapor recovery on the Gen II.

But really other than this issue which is easily dealt with the car is pretty good. And if you keep after the trans fluid and the Inverter coolant and don't pummel it on hills it will easily see 250,000 miles.
A very good car.

 

Thanks for all the information guys! I've had 2 fillups and using the ignorant mindset of topping off each tank to get the maximum range on my car, I've now seen the light! I will vent and fill at 2 pips from now on. Didn't know how cool this car is until I get it in everyday!

 

I always fill the tank at the slowest rate the dispenser nozzle will allow. I have not been venting though. I'll try that from now on to see if it brings the computer mpg nearer my calculated values.

 

From what I have seen over the time I have been checking the mileage and comparing the numbers to the computer, it seems the computer reads a little more than actual mileage. My last average over a four month period: by the numbers 46.625 MPG, by the computer 47.8 MPG That was during the winter to springtime here in Houston.

I have seen other's post similar info here on PriusChat discussing a discrepancy of the actual MPG over the computer stating that the computer is a little conservative, other's will say it is very close. 1.2 gallon MPG difference is pretty close, so I have to say that overall the computer should be a "good ballpark" figure.

Venting does help though in filling the tank imo. If I don't vent I run into problems with the pump shutting off prematurely. That is why I recommend the venting.

Note: Page #81 2009 Owner's Manual. Always hold the grips on the fuel tank cap and turn it slowly when the fuel tank cap is loosened. A whooshing sound may be heard when the fuel tank cap is loosened. Wait until the sound cannot be heard before fully removing the cap. In hot weather, pressurized fuel may spray out the filler neck and cause injury.

Due to that statement plainly written it appears that there may be residual pressure in the tank if you don't vent the system before refueling. Note that I use the word "may".

We have to remember that the gen 2 has the bladder in it. Because of the bladder not every fill will be the same. But it does stand to reason that if there is any pressure whatsoever, the fuel pump will cut off early (premature) which will cause the bladder not to refill properly, hence causing the problem that most of us are running into.

Ron (dorunron)

 

Once you open that tank cap, the pressure in the bladder has equalized with atmospheric pressure. There shouldn't be any time to equalize needed, it should be immediate. I don't understand why venting should help at all, actually, unless the bladder is at a slight negative pressure, then I suppose some time may be needed to let the bladder material relax.

 

Here's my complaint....or better yet complaints: Leaving the driveway this morning with the gauge reading 4 bars and driving 2 miles to the grocery store to find it reading 1.

Having a tank which supposedly is rated to hold over 11 gallons and never coming close to that on refills even when the gauge reads near empty...in some cases blinking empty.

The endless time it takes to try and fill the tank because any attempt to pump at regular speed causes it to trip. Instead, you try to delicately hold the pump handle just enough to keep it trickling, but not so much that it trips.

Trying to guestimate what full is, only to have the tank suddenly respond with a massive burp of air, shoving a quart of gas back out the fill hole, down the side of your car and onto your feet, and then suck gas back into the tank once the air has escaped.

Owning a 2004, knowing that complaints about this problem have been constant and watching Toyota finally move to correct it SIX years later.

I love my Prius in so many ways, but this problem and the horrid blind spots in the rear are the two major problems I have with the car.

 

just a little update on my 2004...110,000 miles...no gas filling issues. when it's empty i fill (well, now the state of OR fills for me!). what ever goes in gets burned. repeat. and i must be used to the "blind" spots. no issues there, no close calls, no accidents. YMMV, but some of us do not have some of these issues. Perfect car? no. as close to perfect for many. Different? hell yeah it is. but in a good way!

 

Your gauge definitely has a problem if it swings that much.

 

While filling recently the nozzle did not click off and overfilled and spilled most a gallon on the ground. Yes I know I should have been paying more attention. I used to rebuild gas nozzles and tend to trust them too far. My question is : Did I damage the charcoal filter? The pump said 11.5 gallons and since that fill up I have driven 186 miles and no redution in pips. Avg now on mfd i58 mpg When I nearly always avg. 48/49mpg .Any answers?

 

I appreciate all the advice! Since my original post, I've had to fill up 4 more times. Each time, I vented the tank for at least 2 minutes before filling, and 3 times, used the slowest autofill setting. Going down to 2 pips I could still only put in between 5.2 - 5.9 gallons. This last time, I went down to 1 pip and filled the tank very slowly by hand - only a trickle, I think, but I got 7.5 gallons in, so maybe it's improving.

I guess I'm still just confused about WHY I can't put 9-10 gallons in an 11.9 gallon tank when I get down to the low setting on the gas gauge. Sure, I have a range of ~350 miles, but I expected a range of closer to 450 - 500. I know people will tell me it's the same mileage, regardless of how many times you fill up, and that's true.

Well, on second thought and thanks to this forum, I guess I understand WHY I can't do a typical fill-up - but I'm just frustrated about it. Again, I appreciate all the suggestions, and it's nice to know that I'm not doing anything wrong and that it's not just me being unable to fill a tank properly!

 

The only real problem is that Toyota listed the gas tank as an 11.9 gallon tank. This sets up false expectations. If they had called it a 10 gallon tank everyone would be satisfied. Technically it is 11.9 gallons, since that is the gross capacity, the but the difference between gross and net is greater on this car, leading to frustration.

Tom

 

this is a car, not a religion.

On the internet - everything is religion (apparently)

 

Help...New to Prius. Just bought a 2001 w/66K the other day...What is this I hear about gas tank gauge being inaccurate...Does this apply to me? Should I worry about running out of gas? The book says I have an 11 gallon tank...do I really. After the read of part of this thread I am thinking about putting a 1 gallon gas can in the trunk and seeing just when I run out...Is this a good idea or not?? Will it hurt anything if I run the tank all of the way out of gas?
Thanks
Darrin

 

Hi Darrin,

Should you worry about running out of gas? Only if you ignore the gage and the last flashing pip. Put fuel in the car when the gage gets down to no lower than two pips on the gage, and you won't have any problems.

The book says 11 gallons... You have to remember the Prius has a bladder in the tank. You will find that the amount of fuel will vary from fill up to fill up irregardless of what the gas gage reads. Don't worry about it. Just put gas in it as I described above.

Do NOT top off the tank. Fill it slowly until the pump kicks off, then hang the nozzle up and you are done.

Don't worry, be happy & Welcome to Prius Chat.

Ron (dorunron)

 

I just put 11.2 gals. of gas in my tank. The most before was 10.5 gals. I let it vent while I paid for the gas and pumped really slow. It helps that the station is not busy and I can go as slow as I want to.

 

That's fighting the emission-system in 2 different ways (allowing evaporation and flooding the vapor canister). Is an extra 0.7 gallon really worth it?

 

The most I have gone without filling was 470 something miles I believe (though I know I can get up to 540 miles a tank) . I have not not noticed anything out of the ordinary with my gauge, I fill it a lot of times after it has been blinking for a day. I do notice sometimes when I get as a Fry's/ Kroger for those in the east it clicks off every other quarter of a gallon so it takes ages to fill it up. SO basically I have not noticed a problem with my gas gauge

- for note the Prius I have is a white 2006 model with around 80k miles.

 

I'm always bemused by the gas tank trepidation. Maybe I'm lucky, maybe European Prius's don't have a bladder, maybe our pumps are calibrated to a different flow rate but I've had a completely different gas filling experience to most on this thread.

The car, an 04 Gen II has been the family weekend car and my wife's daily driver for the last 6 years/65,000 miles. I've done most of the gas filling over the years and was a religious 'topper off'er. I would almost always wait till the last pip was flashing and 'add fuel' warning message beeped and filled her right up till I saw it in filler neck. I can confirm that the tank is a 45 litre tank = 9.9 Imperial Gallons = 11.9US gal. I've often put 44 litres in it. My range is the MFD fuel economy x 10. So if the MFD says 48mpg (imperial), I know I'm good for 480miles. If it says 53mpg, I'm good for 530. I've never ran out of fuel.
As of a month ago the Prius is now my daily driver. The first thing I did when it passed into my hands was to fit cruise control (thanks to the help on this forum!! I'm kicking myself I didn't stumble across it years ago) and on the last 2 tanks I've hit 56+mpg. The car is outside the door right now with 3 pips showing on the fuel gauge and 430miles on the trip counter with 57.5mpg as the trip average so I've def not done any lasting damage to the fuel system despite what appears to have been the most appalling abuse of an apparently delicate system.

The car also fills with gas no problem, I even use the gas cap to keep the handle pressed (most garages have removed the locking clip from their fillers). The fuel guage is very accurate and the trip computer calculates mpg within a single mpg of calculated fill to fill. (having said that, the speedo is nearly 10% over-reading on speed and I've never actually checked the driven distance of the oddo for accuracy - thats on the to-do list now )

I've done everything wrong but the car is just fine.

Now admittedly since reading through the gas tank threads here over the last year I no longer top off so aggressively, just rounding off within a litre after the first click - ignorance was bliss for years but I'm not taking any chances with the vapour recovery system (if its fitted!) now that I'm a little more educated. Also to be fair, 95% of the fills have been at the same gas station and most of those at the same pump so I might just have been the beneficiery of happy coincidence for all those years.

For those who don't trust the gauge, put a gallon of petrol in a can in the trunk one day and go out and drive it till it tells you to add fuel (about 10miles after the last pip starts to flash). Add the gallon and go to a gas station and fill her up to the neck (the system has to be designed to deal with it at least once - I mean I did every time for 5 years). You now know how much fuel is left in the tank when she says its empty and how much it takes to fill it.