My 74' CB360 runs perfectly if I let it sit with the petcock on and take the lines off the filters to kind of encourage fuel flow. It'll ride for five minutes, but after that, one cylinder cuts out. The filter is empty for said cylinder, but when I pull the line off, fuel flows nicely out of the filter. It seems like there is some kind of vacuum being created somewhere causing fuel not to flow until I pull the line off the filter. Does anyone know where the problem is? Does the tank cap seal have to do with this because mine is pretty crusty.