NO fix for Prius Gas Tank Filling Up Issues

[Navigator]

Yesterday, the last pip started flashing (I usually fill up with two pips left). I went to the fuel station, put the pump nozzle into the fill hole as with any other car, and pumped at full speed. The pump clicked off at 8.5 gallons. When I turned on the car, the fuel gauge slowly made its way all the way up to 10 pips full.

I have never, ever gotten more than 8.7 gallons into the car, and I don't expect to. Some fuel must remain in the tank, the secondary tank, fuel pump, and fuel lines all the way to the engine. If you empty these components, you'll enter the fuel station on battery power alone (not good). I have noticed that the bladder capacity varies a bit at every single fill up, but the guage reads full every time. It is easy to see that if I am averaging 334 miles per fill up, and typically put in 7.5 gallons, then my car is averaging 44-45 mpg, in the city during winter. My last car was a 4-cylinder that averaged 19 mpg under the same conditions. So, for sure, the Prius is getting better mileage on the streets. Oh, and by the way, my last car had a "normal" gas tank, and the fuel guage always screamed for more fuel when there was 2 gallons left in the tank. The Prius acts no different, in that department.

Okay, so there was one thing I did do differently, yesterday, than I would with any other car. When I put the pump nozzle into the fill hole, I could feel resistance due to the rubber seal being bone dry. To correct this, I withdrew the pump nozzle and gently dabbed a few free drops of fuel onto the seal; friction was then gone. I rotated the nozzle a bit to seat the seal around the nozzle and then proceeded to fuel as usual. As I recall, some users on this forum have found that seating the rubber seal correctly improves the fueling experience. So far, I have found this to be true.

Okay, just some thoughts on fueling the Pump & Pray Prius.

[CharlesJ]

Originally Posted by Navigator

Yesterday, the last pip started flashing (I usually fill up with two pips left). I went to the fuel station, put the pump nozzle into the fill hole as with any other car, and pumped at full speed. The pump clicked off at 8.5 gallons. When I turned on the car, the fuel gauge slowly made its way all the way up to 10 pips full.

...

I would say that you had about 3 gal left+ 8.5, = 11.9 That's what the manual indicates when the light starts flashing anyhow.

[Genoz World]

interesting. when i am five pips down, half a tank, i can usually get about 5 gallons in the tank when i'm filling up. however, interestingly enough, the other day, i was only THREE PIPS DOWN, i decided to fill up because i was on a long distance trip and got in 7 gallons!

what gives? is this the bladder stretching? my car is an 08 with 15K miles.

[qbee42]

Originally Posted by Genoz World

interesting. when i am five pips down, half a tank, i can usually get about 5 gallons in the tank when i'm filling up. however, interestingly enough, the other day, i was only THREE PIPS DOWN, i decided to fill up because i was on a long distance trip and got in 7 gallons!

what gives? is this the bladder stretching? my car is an 08 with 15K miles.

Capacity varies by temperature, age, refueling pump, and perhaps the phase of the moon. Get used to it.

Tom

[Navigator]

Originally Posted by qbee42

Capacity varies by temperature, age, refueling pump, and perhaps the phase of the moon. Get used to it.

Tom

Which is why I don't think we should be concerned with how much fuel is still left in the car when the last pip is flashing. Once you're down to a flashing pip, you really have no idea how much farther you can drive, at least until the ICE just stops running .

The only concerns I have with the Prius fuel system is potential for non-stop clicking off of the pump nozzle during fillups and the surprise overfilling/barfing gas problem. Both of these problems seem to me to be due to a malfunctioning valve somewhere in the fuel system not allowing pressure to release as the bladder fills and expands. Other than those two issues, the Prius acts nearly no different than any other car.

[Navigator]

Originally Posted by Genoz World

interesting. when i am five pips down, half a tank, i can usually get about 5 gallons in the tank when i'm filling up. however, interestingly enough, the other day, i was only THREE PIPS DOWN, i decided to fill up because i was on a long distance trip and got in 7 gallons!

what gives? is this the bladder stretching? my car is an 08 with 15K miles.

I know we all like to start a long trip with a full tank, but with this car I wouldn't even bother filling until I'm down to 4 pips, tops. Consider, if your car took 7 gallons, that means you had, maybe, 4-ish gallons in the car before fueling. On the highway, my car easily gets 47 mpg with normal driving. But let's assume 45 mpg just to be safe. Assuming our cars behave identically, 45 mpg x 4 gallons gives you 180 miles to find a fuel station along the way. That gives you plenty of distance to find a station when your tank is down to, say, 2-3 pips.

Another technique that I use is to reset my trip odometer at each fill up. My car has consistently gotten about 335 miles by the time I'm down to 2 pips. The car usually takes 7-8 gallons at that point. Using the trip odometer will give you a means for cross-referencing what the fuel gauge is showing.

[Genoz World]

yeah, i got it, but this variance is really a big number.,,,,,,,,i'll wait for another blue moon!

[CharlesJ]

Originally Posted by qbee42

Capacity varies by temperature,
Tom

The Bentley repair manual on page 2-10 indicates that capacity changes by 10% when the temp is 14F; that is about 1.2 gal at 14F.

[finman]

Jesus people, just sell your Prius and drive something else. It really isn't a big deal. Why oh why are people driving something that they can obviously sell (Prius market is much better than other cars). Either put up with the "problem" or drive another vehicle that "seems" to work "normal". Many seem NOT ready for new tech in their vehicles...

Yes, I reallize other cars may have low emissions with no bladder...SO BUY IT! What's seems to be the hold up?

[jalynn2]

I've read a few owners write "I know there are x gallons left when the gauge starts flashing". A word or warning: No you don't! Think of the flashing to mean "Get gas NOW!!!".

My last car (Honda Odyssey) was good for at least 70-80 miles when the low fuel light came on. That's the mentality I had when starting to drive my Prius. I was on a long trip on the PA Turnpike where there's very limited access to fuel and the MFD said 56 average MPG. I went about 60 miles on 2 pips, but the gauge started flashing only 10 miles after dropping to 1 pip. No big deal, I thought, there's a gas station in 20 miles. 11 miles later, the dash lit up like a Christmas tree -- out of fuel.

I never go on a limited access road any more with less than 3 pips.

Forget that the owner's manual says 11.9 gallons. As others have said, you can only count on the capacity being whatever you put in on the last fillup. Also, my MFD reads a bit high: After 26000 miles, the total MFD-estimated MPG is 49.8, but my actual calculated mileage is 48.1.

You've been warned.