tewks

I have twin merc 7.4 inboards with the belt driven fuel pumps mounted on the water pump. (Gen VI block, Mark V heads, carburetor with mechanical fuel pump...not the setup I would choose today!) When I bought the boat 4 yrs ago, both pumps were bad, the lubricant in the water pump housing was diluted with gas, and they were replaced with "genuine mercury parts". Two years later, while putting the boat away for its longs winter nap, again I find fuel in both the water pump reservoirs! Again, I replaced them. Now, two more years have passed, and once more, both the pumps have apparently failed. Question... is this normal for these pumps??? Vibration perhaps from the odd mounting?? More importantly, does anyone know of a replacement I can use? I once had a v6 with a carb and an electric fuel pump, but I've never seen that setup on a carbed bbc. Anyone know of a kit to retrofit an electric fuel pump to a carbed bbc??