Fluidmaster value turns on/off, flush valve is new also.

I recently (2 months) replaced both fill and flush valves in 2 toilets with Fluidmaster products. A week ago I noticed both toilets fill valves are turning on even though the water level in the tank is at the full mark. (Note: the water level at the full mark is below the overflow tube.) The fill valve runs for about 10 seconds before turning off. I did a test where I slghtly lifted the flapper allowing water to leak slowly into the bowl and found I had to allow the water level in the tank to drop at least 1.5" before the fill valve turned on. Therefore, this does not seem to be a problem with leaking around the flapper but a fill valve problem. Any ideas of additional adjustments I need to check/make? Thanks!

Despite your description, the first suspect is siphoning through the refill tube. Make sure that the little refill tube is held ABOVE the top of the overflow. If it is stuffed down inside the overflow, it will slowly siphon water, causing periodic cycling of the fill valve.

You did NOT use the "refill tube clip" that came with the Fluidmaster, but shoved the refill hose through the hole on top of the overflow pipe. You shoved it down too far. Take it out and cut some of the end off.

Another thing to check is to turn the water supply off and let it sit overnight to see if the tank empties. If so, then you have a problem with the flapper valve. You could have both a refill tube issue and a flapper valve issue since you changed them both. If the flapper valve was one that had a ring you pushed over the refill tube verses ears that fit over tabs, that can distort the flapper to cause it to leak.

hj said:

You did NOT use the "refill tube clip" that came with the Fluidmaster, but shoved the refill hose through the hole on top of the overflow pipe. You shoved it down too far. Take it out and cut some of the end off.

Click to expand...

I "DID" use the metal clip provided and mounted the clip and tube per the instructions above the overflow pipe.

jadnashua said:

Another thing to check is to turn the water supply off and let it sit overnight to see if the tank empties. If so, then you have a problem with the flapper valve. You could have both a refill tube issue and a flapper valve issue since you changed them both. If the flapper valve was one that had a ring you pushed over the refill tube verses ears that fit over tabs, that can distort the flapper to cause it to leak.

Click to expand...

Good idea, I'll shut the water off and check the next day. May also try food dye. The Fluidmaster flapper attaches to ears on the overfill tube. Thanks!