My toilet is filling very slowly with a Fluidmaster valve, how do I fix it?
So having done this myself, I spent the money and bought a new Fluidmaster valve. After replacing the valve and connecting everything the toilet was still not functional. Turns out the problem was the flushing of the pipes was not good enough, the Fluidmaster had to be flushed. I flushed a gallon replacing it, and that simply was not enough.


Turn off the water.
Unscrew the cap on the Fluidmaster valve
cover the top with a cup
Turn on the water and allow it to spray into the cup until the water is clear, then wait 5 more seconds.