Plumbing question (simple fix, I hope): toilet tank flapper closes to quickly

So, the other day, I was finally finishing up the big project I was working on, and things seem to be working very nicely.

I wound up replacing not only the seat and the fill valve but also the feed tube (I think that’s it - the part that goes from the shut-off valve at the wall to the bottom of the fill valve), the handle/lever assembly, and the flapper. No leaks yet, but do I have a small issue.

When I flush, everything is fine if I hold the handle down until the bowl is emptied. But if I just press the handle and release it, the flapper will close almost instantly, preventing a complete flush.

Where did I go wrong?

ETA: Aside from spelling “too” wrong in the thread title. :smack"

the flapper valve should have some buoyancy to float and not come down until the water level drops below it. a style of flapper valve is hollow rubber where air gets trapped inside to float it. other styles are foam.

if the valve looses buoyancy then it drops early.

This is a hollow rubber type. I see air coming out from under it when it’s lifted.

if it leaks the air then it is no longer buoyant. if the chain lifts it too high then it might spill the air. if that is the case lengthen the chain so it doesn’t lift so high.

Shorten the chain. The flapper is not liftime high enough and is being pulled down causing a short flush. If the flopper is lifted higher it will float on top of the water until the tank is empty.

If it is floating now and shor flushing then raise the level of the water in the tank.

sipple test ligt the flapper completely by hand and check for a short flush. If it short flushes adjust water level. If you get a good flush shorten chain.

After doing some other looking around, I strongly suspect this might be the problem, actually. I would describe it as “spilling air,” and I would definitely say, knowing me, that I did not give the chain much slack.

The chain should have about an inch of slack.

I recently replaced my handle and the flapper was instantly closing. When I flushed with the top removed, it worked perfectly. What was happening was that I had tightened the handle too much and it was lifting so much that it was striking the top causing the flapper to instantly shut. I loosened it so much that the handle is really drooping now. I now have to hold the handle lever a second and everything works fine then. I suppose I could get a different handle, one that works better with my toilet, but I can live with what I have. Try flushing with the top removed and see if it works. If it does, loosen the handle a little.

Some of the flappers are adjustable, you can set them to close earlier to save water. I am not sure how they work but the one’s I have seen adjust by turning the rubber plug part. Look to see if there are any markings on it indicating it might be adjustable.

This. Some new assemblies are designed to behave this way purposefully so that the most common flush–urine–will use minimal water. The design requires that you hold the lever down for a full flush when you have a more aromatic experience.

I have two low flush toilets with this feature. No problem for us, but when we have guest over they do not know this and plugged toilets. I shortened the chain on each so there is no special flush.

To my absolute astonishment, this turned out to be the correct solution. I don’t know how I didn’t notice the adjustment scale on the thing when I installed it, but when I checked, there it was, set near the “min” end of the scale. I turned it to “max” and now it flushes perfectly.

Thanks, all!

Mods, asked and answered. Feel free to close this up.

This solution has worked for me on more than one occasion.