Well, I had to transfer some water this morning and so needed to run the engine for several minutes. Same problem - died after 45 secs with fuel starvation. Pulled the very fine filter out from the sediment cup and the engine then ran without stopping for the next 10 minutes, with the tank cap fully on. So, I think that the sediment cup filter has been the cause of this fuel starvation. I suspect that the fuel has got just enough viscosity to only just make it through the filter under the very small gravity pressure head from the tank, and in the cold conditions (Canberra area) the viscosity increases enough to prevent the fuel from getting through fast enough to keep the float bowl filled under full load. I use clean fuel and so I don't think that I need the sediment cup filter, so I'll be leaving it out.
