My Gen.2 -Now only holds 31/2 gallons of gas in the tank bladder

I wonder in a situation like that if the rubber is just stiff or if there has been a leak and there are 6 gallons of gas between the bladder and the tank wall.

 

Are you happy with the car, other than the fuel tank? Is it in nice condition and worth keeping if not for the fuel tank? If so, maybe it's worth just replacing the fuel tank? Complete used assemblies are easily available if desired. I have a salvage yard about 20 miles from my house that actually offers mechanic services also, where they will install purchased parts for a reasonable fee. They have 2 lift bays and seem to stay fairly active. Maybe you could find something similar by calling around.

Or do you have your eye on another car and this is a good enough reason to let it go and move on to something else?

Both are reasonable options.

 

Sometimes, the pump nozzle shuts off early because of another issue somewhere in the onboard refueling vapor recovery (ORVR) system, and gets misattributed to the bladder because that's a part of the system that people have usually heard of.







More info in this post and following.

 

still goes farther than a leaf...

 

I'm in agreement with ChapmanF.

The bladder gets far too much blame for a lot of things. Having a car with no bladder, all the symptoms I've ever read about that are attributed to the bladder happen in our cars. So I would encourage people to drop these ideas and start thinking about what is actually going on.

I have only read of just a few threads where the OP followed Chapman's train of thought and successfully fixed their problem. Interestingly, the faults were not the same, but nevertheless, they were in the fuel EVAP/ORVR in the back.

 

Are there any DTCs on the OP's car? If not, is it known in what ways this system can fail so that the tank won't fill fully without setting one?

I have seen that diagram before and I'm sure it makes sense if one already understands in detail how this system works. Me, I look at it and see what looks like an air tube starting at the fuel pump (the piece at the far right), it goes, up, left, up, left, then curves down into the filler neck. No valves Seems unlikely that the fuel pump has a direct connection to the outside air. I guess it wouldn't if the cap is on tight, then it would have a connection back into the gas tank. There are arrows showing flow in that tube from the filler neck, and from the pump. The arrows make sense I guess if the valves are open to the charcoal canister. If they aren't what happens? I suspect this is supposed to show that the air to flush the canister can come from either/both of those directions when the refuel check valve and the two purge valves are open, so that there is vacuum on the throttle body side of the canister.

This was an interesting related read:

Gas From Pump Slowly Goes In, Then It Spills Back Out (Part 2) | PriusChat

 

Does it make a difference if I fill the tank with the Prius powered off completely vs putting it in park but still in ready mode? I tend to fill the tank when it gets down to 2 or 1 pips but I always just put the car in PARK/READY. I do this with other ICE cars so I can watch the dash gauge fill up to full as the pump runs.

 

Best practice is to always switch a car off when refuelling. With the Prius specifically, it should be IG-OFF, not READY.