Thanks Steve, i did try the garden hose down the filler pipe as you kindly suggested. There's a small flap under the filler cap, so pushed through that, them 18" downthe tube there's what seems like another flap, so pushed through that and into the tank i would imagine. I didn't go far beyond this second flap as it was digging into the pipe as i pulled it back again and trying to prevernt the withdrawl.Didn't seem to be a blockage . I assume that the rising head of fuel as you are filling must open this bottom flap and let petrol into tank? Mike