I apologize if this is a second post. This my first time using this forum and not quite sure if I know what im doing. I have 1989 mercruiser 270hp alpha 1. Was out cruising yesterday and when I was docking the engine cut off. had to try several times to start and it cut off again and when I did get to dock I noticed no oil pressure. if engine had not cut off and hard to restart I would say it is sensor but when I tried to restart awhile later the oil pressure was at 3 lbs. I have never had problem starting engine. I had been out cruising for about 30 minutes and engine was running good,. only when coming in to dock did it cut off. I put boat in water on Friday first in over year. had run boat in yard with good oil pressure before launching on Friday. How difficult is it to repair or replace oil pump? or would it be worth it since boat and engine is 1989 model. Where is oil pump located in engine. Had plenty oil and it was good and clear. have not run boat very much in last 6 or 7 years. what could be problem? Thanks