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I am in the Virgin Islands and there are not many Yamaha mechanics. So I have had to go to a OMC guy. My problems start out with a loss of power and fuel flow. Usually after about 20 minutes of running time. We replaced the O2 sensor. The problem persisted and we discovered debris in the fuel reservior and that the filter on the high pressure fuel pump was clogged. We replaced the filter and the problem was solved. The next thing to occur was the engine would not stay running after starting. The fuel pressure would drop to 12 lbs and cut off. After much coaxing and throttle work we could get it started and it would run fine until we cut the engine and tried to start again. We disconnected the throttle sensor and it started up fine. So we replaced the throttle sensor. Next time it did the same thing low fuel pressure. So we replaced the high pressure fuel pump even though the old one came on when you turned on the key it would not sustain the proper pressure. We have also replaced the diaphrams on the manuel fuel pumps. The last thing done was to check the wiring diagram and the connection from the high pressure pump to the fuel injectors and they are ok. So now I have all new parts and sensors and when it used to start fine I can not get it to start and remain running. THIS IS KIND OF LONG but if anyone has any ideas I sure would like to hear from you.