I have a regular toilet about ten years old with 8 month old
fluidmaster or similar guts.
When I flush I get a 'regular' flush in about 4 to 5 seconds then
another flush right after (without me doing the flush). The bowl
fills, flushes, fills and flushes. When looking into the tank, it
appears there is enough water left after the first flush to complete
the second flush before the flapper falls. The tank level is the same
as it was prior to this oddity. One odd thing is I can hear a gurgle
flush through my bathtub as if there is a blockage but all drains go
down quick with no backup.
Any ideas on the cause of the mystery flush and a remedy?