Toto bowl doesn't always fill completely

I've just installed a Toto Clayton (1.28, elongated), and it seems to flush fine. The amount of water that fills the bowl after each flush, however, isn't consistent.

If I hold the lever down for about 1 second when flushing, the bowl seems to refill completely. I measure a water level of 5 1/2" below the toilet rim, and all of the horizontal portions of the bowl are covered with water. Adding more water to the bowl doesn't change the level, so that seems to be the trap level.

If I flush quickly, just a full press on the handle and immediately release, the flush works fine, but the bowl stops refilling at 6" below the rim, leaving some of the horizontal area in the bowl dry and exposed. I've checked the tank water level, and it's set at 1/4" below the overflow pipe.

That extra 1/2" of water makes a big difference. Any idea why it's not filling completely and how I can correct it? Thanks.

 

The fill valve is draining into the overflow tube, just like your picture shows.

When I flush-and-immediately-release, there is very, very little water left in the bowl after the flush. When the tank finishes filling, the bowl hasn't filled up yet.

When I flush-and-hold-one-second, more water is left in the bowl after the flush - almost like some washes back from the trap after the flush. That means it takes less water to fill the bowl. Also, since more water leaves the tank, the refill cycle runs longer, allowing more water to fill the bowl as well.

The bowl should completely fill, even with a flush-and-immediately-release, shouldn't it?

 

The flapper should lift to the same point regardless of how you push the handle, and thus it should dispense the same amount of water EVERY time. If this is not happening check the flapper action as you flush it both ways to see if there is a difference.

 

If there is too much slack in the chain to the flapper, it won't get pulled completely open. Leave only a minimum of slack so the flapper will seal properly and take out the rest. See if that makes your flushes more consistent.

 

Thanks for the replies. I've checked the chain, and there's almost no slack - just enough to let the flapper close completely.

I'm willing to try replacing the fill valve if there's a chance another one might give a slightly greater ratio of water into the bowl. I've seen elsewhere that Korky's 528T can be used on Toto toilets, but when I called Toto the technician said Korky valves won't work for my Eco Clayton. He acknowledged that the Korky 528T can be used for G-Max systems, but not for the E-Max that I have. He said the only fill valve that works for the Eco Clayton is the one Toto sells -- part number TSU28A according to my manual.

Is that correct, or is he just sticking to a Toto script that he's been told to follow? Has anyone successfully used a Korky fill valve on an Eco Clayton or other E-Max toilet?

 

Toto pays the manufacturer of the valves it uses to balance the bowl/tank fill ratios so it actually uses the specified amount of water without any excess going down the drain (if it is trying to put more in the bowl), or fill the tank before the bowl is full. Getting the proper ratio, if you aren't trying to get maximum efficiency, is a potshot, if you try to do it yourself. there are probably a bunch of valves out there that might work, but you'd end up using more water than specified.

 

Okay - so I'll stick with the original fill valve and tinker elsewhere. If I can't get the bowl fill level resolved, I'll see if I can persuade Toto to send a replacement fill valve.

As my first trial-and-error attempt, I moved the black plastic float down the chain toward the flapper by one link. I had to move the retaining ring under the float down one link first, and then I could move the float and plastic retaining clip down one link as well.

I'm guessing that the toilet now uses slightly more water on each flush, but the bowl is now consistently filling just a little higher. It doesn't seem like I should have to make that kind of adjustment, but it's also not a serious modification. Any thoughts?