
When screwing in one of the mounting screws a small "sausage" of silicon fell into the tank. This then morphed into something many times the size and finally lodged itself in the fuel transfer pump.
A small piece also made its way into the main tank. Fortunately that has a finger filter at the outlet so the engine was never starved of fuel.
Lessons learnt
1) Never use a silicon based sealant anywhere near fuel....ever!
2) Use finger filters at all tank outlets (even ferry tanks)
3) Install a filter on the line between the ferry tank and main tank
Pics show the difference in size between the same blob of silicon before and after being immersed in fuel.