Brand new Toilet tank randomly does not fill.

[unbecoming]

Hi all. Thanks for any help in advance.

I have a real stumper here. I will try to keep it brief. Toilet tank was randomly not refilling. Took off tank lid and barely lifted up the arm that holds the water level adjustment screw and it begins to refill.
A gentle touch worked too. Like a 1 finger tap, not a smack/hit. Fluidmaster 400. Then the toilet would work fine for another few weeks and then RANDOMLY back to same problem.
Tried different settings via shaft height/float adjustments, and water fill adjustment screw. 20 to 100 flushes and back to square one again.

At that point I was pissed and ended up buying a whole new toilet with all internals preinstalled. After install everything worked great for a month or so and then out of nowhere SAME EXACT problem.
What the heck? All plumbing in house in new. Water heater is new. Tried two different lengths of supply lines and both were never kinked ever.

So how can I have the same problem on 2 different toilets one of which is totally brand new?
Thank you for your time.

 

[Jeff Handy]

Plumbing is new, water heater is new, does that mean house is also new?
Please clarify.

If plumbing was old and was replaced, there can be minerals or excess flux or other contaminants that are getting caught in the tiny orifice of the fill valve.

 

[havasu]

If it is an old house, every time you shut off the valve, you will collect crud and sediment, and once you open the valve again, that crud is delivered to the fill valve of your toilet. Your best remedy is to place the supply line into a bucket of water, draining out the sediment, then connecting the toilet.

 

[Riickk]

You might also want to be sure the seal on the fluidmaster is clean, here's how:



Hopefully this will help

 

[unbecoming]

Wow. Thanks for the quick replies. The house is older (30 yrs or so) and in an older town with city water. Because of your replies it got me thinking there may be a connection here. I don't recall having issues until they rehabbed the water plant. I do not know what was done over there but it seemed like kind of big deal. Not sure if any relation tho.
We redid all of our plumbing when we moved in with a new water heater same time (pre city water facility rehab). It improved our pressure and I never have any visual debris in the water. Inspected old plumbing at that time and was pretty nasty inside. All good for a year or 2 even with old toilet with original internals.
I will do what u guys are suggesting and post back to help anyone else with similar issue.
Thanks guys.

 

[unbecoming]

Popped top cap off the fill valve and replaced the little rubber disc / diaphragm inside it. I saw no debris in there, but replaced it anyway. So far so good, but it's only been a week. Still using Fluidmaster 400. Thanks everyone. I won't need to be coming over to use your throne. Least for now.