Fuel problem

A mate had suggested that my fuel problem with Snowdrop might be a blocked vent or a vapour lock so when I took Snowdrop out on a run. As soon as she cut out I got out an removed the fuel cap. Nothing. I noticed some fine white crystals around the filler neck so I suspected fuel contamination. When I got Snowdrop back to her resting place I removed the fuel sender to get access to the tank's contents and my suspicions were confirmed. Somebody has been putting sugar, salt or some similar substance into the tank. I dug out my siphon and drained about 6 litres out of the tank getting most of the contamination out. I was able to separate the petrol from the sugar/salt/watever and put it back in the tank. (the petrol that is!) I also checked the fuel pump and found that the gauze filter had been blocked with rust so I cleaned it out. I hope I can get this car sorted out for a local classic show this coming Saturday.