Incorrect MPG either mfd or bladder tank

You may already have torn the bladder, in which case replacement of the fuel system computer, fuel pump, vapor recovery system or other parts may be in your future.

 

Refueling in Ready mode is another bad idea. The Prius technical manuals clearly show that the fuel system is not designed to be refilled in Ready mode. When powered down, the fuel system valves revert to the proper position for refilling. Perhaps this accounts for the higher volumes that you have experienced. Only time will tell if you are doing any damage.

Tom

 

Larry, please don't misconstrue my comment. I have the utmost respect for what you and Wayne have accomplished and your understanding of the Prius' inner workings and how to take advantage of them. My only concern is whether in a thread with a brand new owner on his first tank who knows nothing about the car, the information you presented will be interpreted correctly. Your interjection that the Prius can hold 12-13 gallons under certain special circumstances could easily be taken by the casual observer to imply that you should be able to get that much gas in every time you fill up. We know from a lot of threads and observation that this is not the typical case. Most people get 7-10 gallons in most of the time. People who don't know much about the Prius, and have the expectation that they should be able to get more in have done damage to their fuel and vapor recovery system in the past. I just want to make sure we are setting a new owners expectations correctly to avoid that situation.

Rob

 

Well, welcome to my world. I have been complaining about the same thing with my gas tank. My first pip disappeared at 77 miles then the next two at 20 miles a piece. Now I am now to 3 pips and only have 250 miles for this tank of gas. I was getting about 51 now averaging about 45 to 46. The amounts I have been able to put into the gas tank varies from 7.41 to 8.94. I keep track of everything but still am a little concerned because of the mileage issue. I thought I would get alot more out of a tank than I am. Marcia

 

Rob, for the most part, I agree with your sentiment. However, one issue you've mentioned has taken on the nature of an internet rumor. I have read countless times here on PC of the warning that overfilling can damage the fuel system/vapor recovery system. But I've read only one instance where an owner has had his fuel tank/ bladder replaced. And it was unclear that the problem was caused by overfilling. Isn't it time to determine just how often this "problem" has actually occurred?

To put this in perspective, I do not recommend "stuffing" the gas tank, especially for new owners. They should learn their particular vehicle for six months to a year, being "gentle" when filling the tank and becoming familiar with the Prius' quirks. But I believe that the fuel system is more robust than this overfill warning warrants.

 

Marcia, 7.41 to 8.94 is pretty normal. Your problem is one of expectations. Like many Prius owners, I suspect you read the specifications and expected to have 11.9 gallons of gas at your disposal. Toyota does the Prius community a disservice by publishing this amount. If they insist on publishing the gross capacity of the tank, they need to put a disclaimer around it in bold flashing letters.

Even with your current mileage, your range per tank is fairly normal for a family automobile. This next comment isn't directed just at you: I can't understand people's obsession with mile per tank.

Tom

 

I guess the obession with the tank and the miles is because Toyota hyped this car with over 50 mpg per gallon. You pay a premium for this car and I certainly did and your expectations grow along with that. I should have waited until I got down to the last two pips before posting, because I'm now down to 3 pips and still going on. I have 322 miles on this tank and averaging 47.4 now. It's just people get frustrated because of the lack of knowlege that the Toyota people impart to them. I was never told about the bladder tank, not a shred of anything. I just figured it was a regular tank just like I've always had. Perhaps I should have read more but I relied on the salesman to do his job and acquaint me with the car which he never did but took my money all the same. Do I like my car, the answer is a big yes. Do I save money on gas, the answer is a big yes. I just feel that Toyota did not live up to the customer service commitment by telling you all the important things that they never did. Marcia

 

Well everyone, I can't believe it myself but I fueled up today with 9.76 gallons of gas. I still can't believe I got that much in without trouble. The last time I filled up was 9/4/2008 with 2 pips left. I went 375 miles and with two pips left again, I filled up with the 9.76 gallons. I read it in the prius chat somewhere to hold the nozzle once inserted downwards and that's what I did, put the gas in slowly, very slowly and it kept pumping away. I guess after everything is said and done, I do enjoy my car and the great mileage that it gets. Going to work I'm getting at least now almost 48 miles per gallon and around town 46, so I'm not complaining.

 

So, this bladder system is QUITE interesting. ONCE you understand what the hell it's doing, it doesn't bother me. I understand the purpose is to take up the air in side the tank to help reduce vapors.

BUT, here's a good question:

IF the bladder continuously reduces the space in the gas tank AS the tank depletes of gas, at WHICH point does the bladder "relax" and expand to allow it to be filled?

I'm in Southern CA./Camarillo area. I am constantly trying to beat my score ... I think it's something to constantly look forward to ... I had close to 500 miles on my tank, with 2 blips left on the screen.... OR perhaps 450 miles, either way, I just knew that I had a good tank ... and I was excited about figuring out the actual miles. My MFD said I was getting 51.5 or somewhere's thereabout.

Well, I stuck the nozzle in, set on the lowest setting, at the gas station I always fill up at ... EXPECTING around 9.2 gallons ... that IS the typical amount I get ... although, ONCE, I got 10.9 gallons in there ... but, that was a trip to ARizona, in 110 degree weather ...

Anyhoos, this particular morning was kind of cold ... maybe 60 degrees or so? Well, I went in while the car was filling ... Came back out, and the little guy was done already .... Only 5 gallons .... So, my natural instinct was "Okay, the hoze tripped itself ..." So, I start topping it off ... and each time, it clicks off pretty quickly ... THEN realized ... "Ahhhhhhhh ... I better stop doing that ... .the bladder probably hasn't expanded all the way to allow the gas in due to the cold weather ...."

So, I stopped, and accepted what I got ...

Got in the car, and low and behold, it showed a full tank of gas ... AND the miles on the MFD automatically reset to 0, but the MPG was still 51.2 or whatever ... So, I pressed the RESET button ...

On this particular tank, I got about 250 miles out of it OR somewhere thereabouts...

So .... physics question ... WHEN does that bladder "reset" so you can fill? When the car is shut off? When the gas cap is opened?

I am beginning to think the best time to fill up is during the mid day .... when it's warmer .... and I'm afraid to let it go past 2 pips..... 1 pip, and I'm panicking..... (WTH - Where the Hell is the gas station!!!!????)

I DO love this car ... it IS fun!

 

Yeah, I couldn't even get in 6 gallons before it clicked this time. How exactly do you aim the nozzil down? I filled the tank as slowly as possible.

 

You know ... I pretty much just stick the nozzle in, identify the lowest setting, have it fill ... and when it clicks .... BAMB!!!! I'm done.... I take it out, and accept what I got...

I mean, maybe you can try and get the nozzle in there as far as possible, but, I don't even do that ...

Just stick it in ... fill and pull out!!!

That's a tight little hole ... I have to force it in there ... tight fit!

 

Put the nozzle in and when it is completely in, hold it downwards and then start filling. I can't believe myself that it worked. I almost was able to pump 10 gallons.

 

If you just drive the car and put fuel in when it says "Add Fuel" all will be well.
AMEN:rockon: