I'm with the others in the float valves as the problems rather than the pump... I figure, at most the pump is putting out 6psi or so, and the float valves should be good up to 10 or so psi. Just a guess on that though.

I don't know how much you like the taste of fuel, so you might bring some fresh now fuel line (1/4"ish) for testing the float valves. Easiest I've found is simply to take both float covers off. Leave 'em right side up such that the floats themselves fall, and blow through the fuel inlet pipe. You should be blowing air through both float valves. Then turn the whole thing (both caps still attached with fuel line) over (such that gravity forces the floats onto the float valves) and blow into that pipe again. If you can blow ANY air through the valves with just gravity holding the floats on them, they're gonna leak. Clean 'em.

It is my experience that new float valves leak as frequently if not moreso than used ones. I can't count the number of times I've bought new float valves only to have them leak and back in go the trusty old valves before I even go for a drive. Never throw away old parts that work...unless you've got plenty of extras.

Oh...and of course, the first thing you do is to tap the top of the float covers with a nearby rock or wrench or bolt or whatever. See if that stops the leak. I have a float valve on my Jaguar that leaks every time I start it cold. Its just become standard procedure to be ready with a large bolt as soon as I kick the pump on.

Good luck with it, and get that small fire extinguisher someone suggested. I never leave home without one in anything with SU carbs...and/or Lucas electrics.

-Matt