OK, three boats in one weekend, including mine experienced vapor lock. None of them driven very hard prior to shutdown, ambient temp in the mid 80's. All mercruisers, one 4.3 v-6, one 7.4l V-8, and mine, twin 5.0L. All restarted and ran fine after a couple of hour cool down. The only thing we all had in common was using Non-ethanol (recreational grade) gas (89 octane) from the local marina. Maybe a bad batch of gas? Anyone others using non-ethanol grade gas had this problem (I know the problem is supposed to be worse with ethanol). Link to vapor lock description http://en.wikipedia.org/wiki/Vapor_lock.
