Well have read the posts checked out the links and still no better. Something is very wrong! Ok it is sugested that the voltage on the lambda sensor should be 0-0.5 lean, 0.5-1 rich. Well on petrol i have 2.5V on Lpg i have 0.03V, regardless of what i do with the Vaporiser controls. So i checked the venturi and i think it is too small, its only 34mm bore, is this too small for 3.9 Litres?