I have a deck boat with a Yamaha 115 4 stroke with 83 hours that has sat for a while. Motor started ok, idles good. When I try to acclerate, it falls on its face; RPM holds steady at 3000 and no power. With a 15 pitch prop, I should be able to red line.Took it in to local dealer and $800 later, I have the same problem. They replaced the plugs, oil/filter, fuel filter, and all of the fuel lines. I have a Racor water seperator that they say checks ok. Fuel checked ok. HP and LP fuel pumps check ok; fuel rail and injectors appear to be ok. They called the factory and were told the problem is most likely the Idle Speed Control (ISC) valve which is now on order. They say that the factory also warned that replacing this valve could result in ECU failure.I am looking for ideas from the members as to what else may be broke. I dont understand how replacing the ISC can fix this problem or break the ECU.I know I should have driven the 80 miles and let Tommys wrenches look at it, but 5 miles to the local dealer seemed right at the time.I appreciate your suggestionsthanksjwt
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