Fluidmaster Fix It Zone
Universal Toilet Fill Valve Won't Turn Off (Instructions for removing the top and flushing debris)
* Removing the top cap of 400 Series Fill Valves
If your fill valve is not turning off and overfilling the tank to the point the water is draining down the overflow pipe, follow the instructions below to remove the top and flush out debris which may be causing the problem.
If you are attempting this procedure while the valve is already installed inside the tank it is necessary to turn off the water supply and flush the tank.
With right hand, reach under the float cup and push it up. Keep right hand under the float by grabbing the valve shaft and holding it tight. Do not let the float cup drop or the valve shaft turn.
With left hand, grab the cap and at the same time place your thumb on the side of the lever arm (see picture) and twist both the cap and the lever arm counterclockwise 1/8th of a turn. You may need to press down on the cap while making a quick twist. The valve cap will unlock. The cap assembly includes; the top cap, lever arm, plastic housing and (242) seal.
Once the top is off hold cup upside down over uncapped valve to prevent splashing. Turn water supply on and off a few times. Turn water supply off before putting cap back on valve.
To replace the top cap back onto the valve assembly place cap assembly on top of gray valve body by aligning cap arm and adjustment rod next to refill tube and press down on top cap while rotating top & arm clockwise to locked position.
The bottom hand is lifting up on the float cup, which raises the black arm at the top cap. The top hand is gripping the cap while the thumb is pressing on the raised lever arm and turning counter clockwise.