Hi Robert,

My engines tend to suffer this either when they are very cold and have been left a while as Alejandro suggested. It seems that fuel tends to congeal and block the feed from tank to engine. I guess I could be more dogmatic and drain the tank every time I finish flying for the day and then run the engine dry at low rpm. I can clear the blockage either by heating the engine externally with a heat gun if I'm at home, or by just cranking the engine till I see the fuel flowing up to the injector. The very worst case might need the needle opening up to help the fuel start flowing and then re-setting.

I'm not sure why the fuel congeals. On my test stand in my garage I have a tank permanently fitted and fuel in the pipes always congeals if left for any time so its not like its anything really to do with the engine as such. It does seem much worse in very cold weather. I guess this is just a facet of the oil used; the congealed fuel does appear to be similar to the oil in its un-mixed state; i.e. quite viscous and deep red.

Best wishes

Keith