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Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3976
Experience:  US Navy (Ret) Certified Mercury Marine Tech with over a decade of repair experience.
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I have a 2001 Yamaha F115 when the engine is cold it goes really

Customer Question

I have a 2001 Yamaha F115 when the engine is cold it goes really well I have a problem without power as soon as it warms lacks power at 4000 rpm it not turn out well. If I throttled to 3000 rpm it runs well mas does not have much power as when it is cold .. I change the spark plug, fuel filter, gasoline full etc. I have the same problem . Rhe moter start very well and run fine in the trottle
Submitted: 2 years ago.
Category: Boat
Expert:  Charles replied 2 years ago.
Hello, my name is***** you for allowing me to assist you today.
You will need to check the ignition when the engine is warm. Use a timing light and just watch the spark on all 4 cylinders to make sure that there is no gaps in the flash.
Test the fuel pressure as well. It should be mid 30's at idle and over 40 PSI when above 1500 RPM.
If those are good, do a compression test on the engine both cold and warm. Let me know what you find out.