Roger - I had that same problem. On mine it was an easy and inexpensive fix. It was the oil pressure switch. They are partially metal and the rest hard plastic and its seal will leak if it is hit accidentally. I lost 1/2 of the oil from the engine and it was all over the galley floor and it was black while I had the engine on at 30 knot wind in San Francisco Bay. Half an hour earlier it worked just fine. Here is what it looks like http://biax.selfip.com/PixAlbums01/1999_Catalina_36MKII/slides/P6160534.html
You can buy a temporary replacement from an auto store for about $ 10.00. Its specs are 5 to 10PSI and it is Normally open. That is when the engine is not running the contacts are open. Good luck I hope this helps.
You can buy a temporary replacement from an auto store for about $ 10.00. Its specs are 5 to 10PSI and it is Normally open. That is when the engine is not running the contacts are open. Good luck I hope this helps.