I live in an apartment, so this should be covered maintenance, but the management sucks and maintenance requests take an eternity to get processed so I’m trying to figure out if this is something I can easily fix myself.
It’s a simple set-up with a Fluidmaster unit like the one at the beginning of this video. Except in that one it’s constantly filling (thus overflowing) while my problem is the opposite - it’s not filling at all. Water is spewing out from the head where the black cap is (and making a really annoying hissing sound), but it’s not coming out of the little hose where it’s supposed to. Unless I turn off the manual shut-off valve on the wall and turn it back on, in which case it starts to fill up normally - but only one time!! After the first flush it stops re-filling the tank and goes back to spurting water from the cap area only.
I’ve done some Google searches that turned up issues that seemed close but not quite the same thing - none would explain why closing and re-opening the manual valve would fill the tank only once. The fact that it does also seems to indicate that the mechanism works. So what’s going on here?
It’s defective because it only works one time. I don’t know why. Toilet valves aren’t that expensive. Go to home depot or lowes and get a replacement. And as seen in the links I provided, it’s not that difficult to replace them. I’ve probably done it a couple of times in the homes I’ve owned.
The fill valve is defective. Rebuild parts are sometimes available. A new one only costs about $5 and is available everywhere. Measure the height of the tank inside. The new one will state that it is adjustable between x>y. If you are in that envelope, buy it, adjust it, and install it.
A complete kit with everything, fill valve flapper and float is only like 30 bucks. When a toilet has an issue I usually just replace everything rather then try to troubleshoot it, takes less time. It’s a very easy process, if needed the instructions are pretty detailed.
IIRC, I had that problem a couple years ago. What happens is that something either broke off or infiltrated the fill valve. It sits in the tube and blocks the water until you turn the shutoff off and reopen it. The rush of water that goes in when you do that dislodges the obstruction for a little while, until it resettles and then you have to do it again. Just replace the whole works.