Gavin and I were up in Bangor (NI) last year for The ribraid

, we were belting along at full pelt when the engines died, when we swaped fuel tanks, all was solved....
switched tanks again .... engines died,

but , only at WOT.
on opening the inspection hatch on the tank, and looking around the fuel system, we found a large amount of clear silicone in the fuel pick up, that had blocked the whole thing up, but only when 40L/h was demanded at WOT and not at 20l/h at normal crusing speed.....
Silicone was pulled, poked and sucked out, which was not easy , and all was sorted........
......and where did this silicone cone from ????? it was a seal , in addition to the rubber O ring seal that sealled the inspection hatch... originaly installed by the tank makers.....

, all traces of silicone were removed, and no problems since.