Toto Ultramax drops water tank level only when water turned on
I heard a sizzling sound coming from my 1.2G Ultramax. I took the cap off the TSU25A fill valve to discover water was spritzing out the top. I called Toto and they sent me a new fill valve even though I was out of warranty. Replaced the valve. A few days later the spritzing was back. I called Toto. They had me check to see if the tank level was dropping too. It was. They had me tighten the screws under the flapper and test to see if the water level dropped if the water supply was shut off.
I ran tests for about four days looking for water dropping from the tank when the water was shut off. Below are the test intervals. Between each test period I turned on the water, flushed the toilet, let the tank refill and shut off the water.
1. 4 pm to 11 am
2. 11 am to 2 pm
3. 2 pm to 11pm
4. 11pm to 11:30 am
5. 11:30 am to 4:30 pm
6. 4:30 pm to 12:30 pm (16 hours)
Not once in the time above did the water level drop with the water turned off.
After about two days with the water turned on I discovered the water spritzing again out of the fill valve and the water had dropped as shown in the video at http://youtu.be/5OsJBToY0Pc?hd=1
The this happens every time. Sometimes it might take a few hours or even longer for the water to start dropping. It does not seem consistent in regard to time.
I do not have a Watts braided supply line. It's a plastic tube. Why does my water level drop only if the water supply is turned on? I have not yet tried the food color test to see if the water from the tank is making it into the bowl.
I have the same Toto downstairs and it does not have this issue, which would seem to suggest it's not a water pressure issue.
Thanks for any suggestions.