I chased a fuel leak one weekend on a Blaster, couldn't figure out where it was leaking from but the carbs were both wet. When I tore them down the last time I managed to catch the problem before the fuel dried up enough. It was the metal discs on the metering diaphragm of both carbs. They were both new SBT kits but for whatever reason the discs did not take a proper seal to the rubber. When you look at those discs, one side has a large diameter disc with holes in it and the stem to contact the needle valve lifter, the other side has a smaller disc. Well, where the rubber is supposed to be sealed in the center between both discs, it did not on both kits. Fuel was seeping past the center merger point and exiting through the vent. After swapping out those two bits with some reasonably decent used ones to get the ski back on the water...it was the last 2 weeks of the season for this guy...the problem was cleared and the fuel smell was gone once the raw fuel in the hull was all cleaned up. The way I found out these discs were defective, while holding onto one between my thumb and finger at the center, I could spin the rubber around the metal discs. It actually freed up so much that they ended up being able to spin like a new wheel bearing on a ski trailer. You may take interest in looking for fuel around those diaphragm covers, it just might be those discs leaking through into the engine compartment.