Many thanks to Dave for the information, and taking the time and trouble to speak to me and give me a run down of what this system does. Also thanks to Tony Ludford (take a bow Tony) for describing the solution on May 13th 2005. Very prescient of you! To recap; this is a saddle tank straddling the exhaust pipe, with 2 chambers connected at the top. The pump is in the O/S chamber with pipes and wires going internally to the Fuel Module (an assembly that, I think, holds the fuel filter) in the N/S chamber. The top of the Fuel Module is a bayonet fit onto the lower section. This had twisted and unlocked. Having spent 4 hours on it (and more hours on the internet and phone) I pressed the top and bottom together and twisted clockwise, and bingo! Engine now starts. Easy with 20-20 hindsight. Phew! Regards, Nick Bell