What would cause this ???

[scotto-]

It really does sound like the petcock (in tank) fuel filter is clogged. Very common problem from expirience.

I just remove them and put a quality in-line filter on instead. A cheap yet effective fix....

The cheap chinese tanks that come with the kits come with everything except gasoline (petrol) in them

 

[allen standley]

16:1 Can't imagine anything would run at all with that syrup mix. Drain fuel -- freshen up with 32:1.