When we flush the water in the tank runs and runs.. until it goes over the top.

Sounds like you have a defective fill valve there smilink:

Tell me which kind of fill valve you have... top or bottom picture?

You may be able to repair the fill valve.. or may even need to replace the fill valve... let me know what you want to do... Mark

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I have the top picture. Thanks!

when we flush the water in the tank runs and runs..until it goes over the top.
Replace the Fluidmaster or flush valve. It's not working properly.

YUP... as otherbill said... replace the fluidmaster fill valve... OR..

You could try to repair it if you want... ;)

If want to repair, need to shut the water into toilet, remove the CAP and ARM by pushing down on the cap and rotating counterclockwise... set aside.

You will see a black rubber seal... remove this, PULSE WATER ON for a second (cover fill valve with rag or can), clean the rubber seal, and then replace real quick and reassemble unit. TEST. If OK, great. If not, may be able to replace the fluidmaster washer (sold at all plumbing supply houses... see picture).

Otherwise, pick up a new fluidmaster 400A... very easy to swap out. Just shut water to toilet, drain all water from tank, loosen water supply tube, and then loosed nut at outside tank... then read instructions for installation on box (go a little tighter than the hand tight they tell you to go on nut).

You may also want to pick up a new closet supply (see pic.) while you are at the home supply store... ;)

Let me know how it goes... MARK

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