One Tank Unable to Fill to Capacity

It was the pump auto-shutoff settings. They vary from pump to pump, and the fuel bladder in the Prius can trip them up.

Tom

 

I've decided that my Prius will do what it wants in terms of gas. If she says she needs gas (down to a pip or 2) I fill her up (usually only 6 gallons or so. And once in the winter, only 3 gallons). Just do what makes her happy & worry about the numbers later. In all cases, the mpg figures from the MFD remain consistent, so I don't argue.

 

I love it. Judy, can you send me some of your patience and flow? 'because frankly, I'm still strugglin'. What you are basically saying is that it's ok to fork over 24 grand for a car that tells me how much gas she wants to take on any given day at any given time? How do you verify the MPG? Where IS the consistency? I'm really trying to find it. I want to be convinced.

 

Apparently you are not happy with the car. Maybe you should sell it and get something with a regular fuel tank to satisfy your need to know exactly what is going on with every drop of fuel.

Otherwise I suggest reading more threads where members provide lifetime fuel measurements and how the MDF and the calculated mpg are very consistant.

 

If you had the car in ready mode it will do this. The vehicle in only ready to be filled with fuel if it isn't in ready mode. That make sense?

 

I'd say it's the pump. The car might vary by a half-gallon or so, depending on changes in temperature from one fill-up to another, but nothing like what you saw.

I once rented a U-Haul truck, drove it 50-some miles moving stuff, then tried to fill it up, and it only took 50 cents of gas, after 3 clicks! Obviously that's not right, and I tried to explain when returning the truck, but they didn't buy it. I should've driven to another pump at the same station and tried that.

Recommendation is to use the same station, even same pump, as often as you can, for best consistency.

 

I had one refill similar to this as well - at the last flashing pip and couldn't get more than 7 gallons in even with a little persuasion (pump kept shutting off). Recalling other threads regarding overfilling and damaging some components in the fueling system, I decided not to force the issue too much.

I chalked it up to some combination of that one pump having a bad day and/or the bladder in some temporarily shrunken state. Certainly a bummer to have to refill sooner on the next tank, but it didn't seem to impact mpg

 

We have about 2600 miles on our car and there was one occasion when the car took less gas than I expected. The mileage went up 7-8 mpg higher than it had been. It caught up the next fill up. The last time I got gas it happened again except the mpg went up 11-12. I expect it to catch up next time. The lifetime mpg is what I care about and that is not going to be affected. This is the only thing about the car that is a little strange. I just don't want to over fill and have some of the problems that I have read about. The dealer where we got the car is having a new owners open house next week to sell us on their service department so I am going to ask about this issue.

I would like an owners manual that explains the car a little better. I have 50 pages on the radio and 10 pages on under the hood. So I really appreciate this site because I can get most concerns addressed by people that seem to know a lot about the car. We love our Prius.

 

As I reported before, I did not think that I had filled my tank on a previous occasion when my mpg had jumped about 7 mpg. The next time I filled up my mpg was less than it had been on average. I filled up today and the mileage increase of 12 mpg that I seemed to get from the previous tank was erased in the same manner. My mpg on average has remained pretty constant. These dramatic fluctuations are caused by the inconsistant filling of the tank. We have 2750 miles on the car in the last 10 weeks so this occurs about 20% of the time that we add gas.

 

this happened to me yesterday at a 76 station... I could only get 4 gallons into the tank when I had 2-3 pips left on the meter. I tried a nearby Chevron station and was able to get another 3 gallons into the tank. I'll probably avoid that particular 76 station from now on.

 

This happened to me with my Prius in IL and was weird. And a little scary given that my trip was about 1300 miles that day.

But it also happened in San Diego when driving an inferior Ford Taurus. So there !

 

This happened to me on my last trip to the gas station. This was the same station I have used several times. I has on my last pip, but the pump only got about 5 gallons in before it clicked off like it was full. I hung up the nozzle, and tried a second time. Only got 2 gallons in. I pulled over to another pump at the same station thinking the issue was with that particular pump. Only got another 1.5 gallons. The gauge shows full, but it doesn't seem possible. The avg mpg showed 48 on the last tank, but I traveled over 530 miles! (I always reset when I refuel) And only 8.5 to fill it up. Isn't that mathematically impossible? Should I be concerned that my gauge is right? I'm still on that tank of fuel. I'll see what happens when I go back to the station (in a week or so!)

 

Your gauge is fine. You can't manually calculate MPGs for one fillup because of the variable capacity of the tank's internal bladder: the amount of gas you put in at any one fillup is never the same as the amount of gas you burned since the last fillup. (Slightly exaggerated example: if you drove 500 miles since the last fillup and can only put in 5 gallons at this fillup, have you been getting 100 MPGs? No, you have not.)

The way to know the car's MPGs is to look at the display. The way you know that you're about to run out of gas is when you see the final pip on the gas gauge starting to flash. If one pump puts in gallons less than you expect, try another pump.

 

Your gonna be really pissed when it soaks your shoes in gas. Thats coming next. Don't stand directly behind the pump! The dreaded gas belch where for no apparent reason a gallon of gas shoots out the gas fill nozzle. Good times. My 07 was perfect till around 5K miles than it has started this gas nonsense. It's not the pumps. I have always used the same pump for the life of the car. Same pump every single time. When the bladder gets a few miles on it, it starts getting cranky.
Not sure if this matters but now when I now go for gas I open the fill nozzle. I leave it open. Go inside for a few and then come out and then put the gas pump in the hole. I let the gas tank vent for a few minutes and it is now back to its nicely behaved self. Maybe it gives the bladder time to expand but so far its working. Oh and always fill up on slow slow. But thats not to say it won't soak my shoes today but the venting has worked for the last 3 fills. But I do love this little car. Oh and the dealer has no clue.I'm pretty sure no one at my dealer even owns one.

 

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