Hello-

A problem has developed in the past few days with my toilet. When I flush the toilet, the water goes down but the tank fails to fill up. When I turn on the bathroom sink, the toilet tank begins to fill and will continue to fill after the sink is turned off. Basically, turning on the sink triggers the toilet tank to fill up.

Any thoughts would be appreciated.

Thanks.

What type of ballcock do you have? Float ball on a rod or a can on a wire?

If I were to say float valve no ball would that help?

If you don't have a ball then you probably have a black can shaped float that rides straight up and down, correct? Tom will do the rest tomorrow.

Correct, black can shaped float that rides straight up and down.

Correct, black can shaped float that rides straight up and down.
OK! You have a FluidMaster ballcock,(see image) that needs a new #242 seal,(see image). If you need instructions on how to change out the seal click on, Fluidmaster | Troubleshooting | Questions and Answers (http://www.fluidmaster.com/troubleshooting.html) and scroll down to #5. Good luck, Tom

Seems to work perfectly now. Thanks. Would you care to explain how changing the seal would fix the problem? Seems a bit strange to me. Thanks if you have time.