Fuel vapourisation

[andrew34ruby]

Adding 10% kerosene would mean that 10% of the fuel has quite a high boiling point, the remaining 90% will still contain the light fractions that will boil in the range 35 to 50 degrees C.  Therefore, adding 10% kerosene might not help much in avoiding vapour lock occurring?

I'm not sure about this. Would the lighter fractions still boil at the same temperature? I'm inclined to think that the mixture will boil at a different temperature, and probably a higher temperature?