Toilet flushing problem

I have a toilet with a Fluidmaster 400A valve.  When the flush lever is pressed, it does not flush,  it stops right away.  If I hold down the flush lever for 10 - 15 seconds and release it, it will flush properly.   I replaced the ball flapper a few weeks ago and there are no leakage problems.  I have looked at the Fluidmaster site and it was no help.

Does it have a two flush system to conserve water.?

A quick push down on the lever resulting a half flush for say a no# 1, and a lingering push down resulting in a full flush for a no# 2.

Or, did this problem just start.?

If you have already replaced the flapper with a more modern flapper and it still didn't work, try to install a new flash valve. Otherwise, let a plumber see the problem.

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plumbing

I suggest that you call a plumber to properly assess your toilet problem. Maybe it needs a toilet part replacement.

I had a rather similar problem with the toilet in the basement which I never use as I use it as a storage. I only found out recently when I wanted to clear out the stuff to be moved to a self storage facility that I have this problem where I need to depress the level for a long time before it will flush. I thought at first the water dried out or something but I checked in the cistern and that wasn’t the case. I have one of those water saving two flushing system mentioned by ron45. What did you do? Did you get a plumber in the end? I would love to turn the basement into an entertainment room and a working toilet there would be awesome.

The question you raise is two fold. First is the water delivery which is the Fluid Master400A. The second part is when you trip the flush lever the flapper doesn't have enough "hang" time to allow most of the water to drain out of the tank. The possible solution is purchasing the toilet flappers that have a foam float attached to the chain. This style has the ability to adjust the foam up or down to increase the opening time the flapper stays afloat.-Henry

I concur with @mew1253's answer.  I had a similar issue with our toilet. Being that the newer toilets are water conserving, the flapper is angled in such a way that it closes quickly to limit the flush.  Either holding the handle down for 10 seconds, or replacing the entire flapper valve assy. with a less aggressive type is the only solution that I found.  I replaced the entire flapper valve assy, in mine, with a Fluidmaster brand.