fuel in vacuum advance canister

Just as the title says im getting fuel in my vacuum advance canister. Its ruining the diaphragm in it then leaking. Im dam Lucky it didn't blow up the distributor or cap! Its hooked to manifold vacuum sorce on the 750 race demon carburetor. The motor is a very healthy 340 with a 242 247 @ 050 camshaft so the reason I have on manifold sorce is for the added timing at idle & cruise. I sstitched to directly to the intake runner to see if it helps or not. Ill run it a bit and see. Anyone else ever run into this before? There solution? Thanks guys.
That's strange. The only way I can think that fuel would travel from the carb fitting too the vac diaphragm is that fuel is being pushed out the fitting instead of applying a vacuum. I can't even see a surging problem causing that but I guess that could be possible? Try running the engine with the vac hose detached and see if it's pushing fuel out.