I have two older Suzuki 4hp motors DT4 that will not pump water out of the pee tube. Both run like a top and have new water pumps. I blew compressed are thru and the tubes and all seems clear ? I?m stumped and wonder if I need to put the cylinder head or power head as it could be clogged up cuz these are salt water run motors. Any ideas, is this a common problem with these DT4?s - thanks