Like I said it doesnt even have to be a leak, just a air bubble in the hose and that can make it look like its sucking a lot of air. I get this almost every time right where the hose meets the racking cane. I just pick the hose almsot straight up for 3 seconds and that small air bubble travels down the line and then its all good. Like I also said this can happen with any type of racking, it just looks mor severe the faster you rack it.