My tank is only 5 Gallons

Hi Justin,

A few questions:

How many times did the fuel pump click off while you were pumping 20 liters or 5 gallons?

What level did your fuel gauge read after refueling?

Perhaps you should try pumping an additional 10 liters?

 

If your gauge is showing 10 bars then you're right. Might be possible to pump 4-5 liters more but 10 would be asking for trouble. Guess your fuel tank bladder becomes really small in the frigid Canadian winter.

 

That may help, on occasion I have only been able to get about 7 gallons in from empty (when its cold), but can't put anymore in. The gauge will read 10 bars, I'll only drive say 10 miles or so. The gauge will occasionally just drop a bar while parked when this scenario happens.
I have previously read on here somewhere where some guy claims he unscrews his gas cap then washes his windows then he pumps his gas, he claims it lets some of the vapors escape and is able to pump in 11 gallons or more everytime.

 

It's a pretty odd tank, that's for sure. Although my fills have been trouble free so far (fill at 1 pip/rarely 2, lowest nozzle setting, off at first click) I don't doubt those who see these problems. For me one tank is 8.7 to 8.9 gallons but the next might be as low as 6.3 (from what I've seen so far.) Some of this is whether I fill at 1 pip or two, but the calculated/vs indicated gasoline usage for these same tanks varies from nearly a gallon under to nearly a gallon over (1.9 gallon variation). 20% variability on the tank is borderline at best.

If I was only getting 5 gallons in from 1 pip, then I would take it to the dealer and document the problem and see if they could find any thing. Assuming nothing changed and the problem remained, next I would probably try packing that sucker to see if I could get the bladder re-expanded. If it has problems after that it is Toyota's problem. It is after all a problem with the design and/or manfucture to begin with. The more outlay they have for improperly functioning tanks, the less likely they are to adorn future Prius' with this unnecessary albatross.

There is a lot that can go wrong with the complex vent system for the tank. The line sizes appear to be too small for the vapor traffic and the design is likely to produce two phase flow choke points during the fill. Adding to that it wouldn't surprise me if ice restricted a line at some point.

 

You may need to have your tank level reset. The dealer can run it through a simple process on a flat surface which will reset the inclinometer on the fuel gauge (you can do it yourself if you wish - the steps are on this site). If the inclinometer is off, you can get a premature empty reading, meaning not as much fuel will go into the tank when you refill from "empty".

Tom

 

This is exactly what I'm thinking. Filling only 5 gallons from the 1-pip mark is pretty extreme even for our finicky cars. The fuel gauge may be reading low.

 

Too bad they can't figure out a way to shunt some of the traction battery heat to the fuel tank to keep the bladder pliable during cold weather.

 

I'm really kind of surprised there is a bladder and not just a "big bucket" style fuel tank. Seems like an unnecessary source of potential problems.

If it's a big bucket, your problem is probably in the fuel guage system, rather than the tank.

If it's a bladder, I'd be real surprised if Toyota didn't work very hard to make teh bladder remain pliable over the full operating range, Especially for Gen 2.

There certainly is a way that Toyota could have heated the fuel tank from a power source: a resistance-wire heater, probably inside the fuel tank. It would need a power controller and a temperature sensor, so it is not a cost-free feature. I'm not sure how great the benefit is. The energy draw would reduce fuel economy. Probably it should be driven by the low-voltage power system for safety.

 

Putting resistance wires in millions of polymer fuel tanks would seem to be a really bad idea on the face of it. Sort of like using an open flame to find a gas leak...

 

How about using a pilot light?

Tom

 

Have you got the ability to put the car in a heated garage? I wonder if the bladder was warmed a bit, if you could fill it properly.
I have noticed that despite the fact that my car is in an unheated garage rather than outside, the tank accepts less fuel as the weather turned colder in the fall. It still pumps enough to go quite a distance though, and it is certainly NOT even close to reasonable temp. here. It is very cold lately!

 

Grinthock,
How are you placing the fuel nozzle into the filler neck? How far in? Do you hold onto the handle and pump or let it sit by itself?

I ask because on the first fill, I stuffed that nozzle in pretty far. didn't pump anything in, just clicked off repeatedly.

I've been saying the following in a lot of threads, but I don't put the nozzle in much at all, and let the handle rest on its own. Set the 'latch' for trigger and wait for clickoff. Never pumped in more than 6.5 gallons, but never gone below 3 pips either.

Hope that helps.

that said, I've never refueled in anything less than maybe mid 40's F temp.

 

My tank is aprox 6.5 gallons cold (below 60F) and 9.7 gallons hot (above 80F).

Its just plain ------->STUPID<---------- that the tank changes sizes. Sometimes I sit there and click and pump for 3 mins try to force more gas into it. Its a real pain in the azz. I know it can hold 9.78 gallons why is it shutting off at 6?

Yet another in a long list of Prius irritations.