Method for inhibiting water ingestion in a four cycle marine engine

A method is provided for avoiding water ingestion through an exhaust system into the cylinders of an engine during an engine shutdown procedure. Air is allowed to flow into the air intake conduit, either through an opened throttle plate or through an opened idle air control valve to raise the pressure within the intake conduit toward equalization with atmospheric pressure. This reduces the negative pressure of the intake conduit relative to the exhaust conduit and inhibits ingestion of water upwardly from a body of water through the exhaust conduit into the cylinder.