Can't fill Gas Tank suddenly -2005 Prius

I as doing a tire rotation and thought I would remove the plastic cover over the filler.

 

Strange... In Washington state,(Oregon too, if I recall) it is illegal for attendants to "top off" tanks. They're supposed to stop when the pump first clicks off. That said, I occasionally would have an attendant attempt to top it off and I would stop them.

 

I filled up at a local convenience store/gas chain here and I asked the attendant if they are told not to top off gas tanks and he said yes. That makes me feel better about the forced full-serve NJ market. I will make it a point to tell anyone that tops off that it could cause issues.

I picked a gas shut of valve locally at a junkyard here. Wasn't too bad to pull that part. The upper valve would be a bear, but I am trying the easy solution first. Used part was $5 and the part new online is $42 + shipping. I am taking a chance that most cars don't have this problem and the picked part is most likely good. I will also check for any kind of fuel in my part.

I am surprised that I have gas gauge irregularities on top of the inability to fill the tank, but maybe its likely more sophisticated than I can mentally handle.

 

I replaced the fuel shutoff valve under the gas filler tube.
I went for a nice long drive this weekend through MD and VA, but it wasn't the kind of trip where I could run out of gas without hearing it. The gas gauge was erratic even though I only refilled about every 150 -200 miles. The gas gauge was never below 1/2 (which is where the irregularities noticed were).
One time when I filled up, it was down two pips and three gallons went in. The gas gauge didn't change to full. And it stayed that way until I used enough gas to drop below that level. The other times it acted normally. ( at least in the 1/2 to full range)
As far as filling the tank, with 150 miles into a trip and about two pips down, the pump filled without shutting off. I let it sit for 20 seconds and then tried again... another 1/2 gallon and then i hung up the pump. It was consistently good. I hope that is not the definition of topping off but I was unsure it was shutting off when it should have.

Now that I am driving by myself, I have another trip this Wednesday. I think I am going to carry 2.5 gallons of gas in a can and see how the prius and the gas gauge behaves below 1/2 full. If I get the weird behavior where it is threatening low gas at 200-250 miles into a full tank.. I may see if I can stretch that to 350. Worst case I fill from the gas can if I stall.

So now the only concering behavior it has was that between 1/4 an 1/2 full, the tank would pretty rapidly go down to 1 pip and then signal the "time to refill" warning. I am planning on testing that again.

Will also see if the NJ pumps cause an issue. All the self serve pumps I used over the weekend were the kind that did not have the vapor recovery built in.

 

I let the Prius use gas without filling and kept track of the total miles. I had driven almost 300 miles and had two pips left on the gauge. There was no strange occurrence of dropping from 3pips to one and flashing a low fuel warning
At the gas station the Prius took about 6 gallons of gas without shutting off
I don’t think I fixed anything but I am comfortable with the way it’s acting