Pilot of a Cessna 172 RG reported a lack of power. Initial investigation revealed nothing. Then he mentioned that he was getting strange globules from the right tank water drain. So we sampled and indeed these cream coloured globules were present.
We fished a whole roll of masking tape out of the tank minus glue.
Complete fuel system was disassembled. Nightmare was cleaning the integral tanks, as as soon as the fuel was removed the glue went hard.
Tanks had to be cleaned out while filled with fuel. Very unpleasant.