Make sure all lines are hooked up properly: fuel tank vent to pressure side of regulator w/ check valve in the line, arrow pointing in direction of tank, and the fuel supply (clunk side) hooked up to the regulated side. Run the engine and see what happens. It sounds to me like your fuel lines may have gotten reversed somehow, and the crankcase pressue is blowing out through the clunk causing bubbles in your tank (of course, the engine wouldn't run long, if at all, if this had happend). Let us know how it goes.