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Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3927
Experience:  US Navy (Ret) Certified Mercury Marine Tech with over a decade of repair experience.
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I have a 2009-2010 Yamaha boat motor which has lost power

Customer Question

I have a 2009-2010 Yamaha boat motor which has lost power due to unleaded ethanol gas
How do I repair it
Submitted: 1 year ago.
Category: Boat
Expert:  Charles replied 1 year ago.

Hello, my name is***** will assist you.

Your engine is designed to burn up to 10% ethanol fuel. Any more than that will degrade the fuel lines on the engine. You need to locate the cause of the power loss, do a compression test, then a spark out out test on all 4 cylinders. Compression should be close to 200 PSI with the throttle open. the spark should jump a 7/16" gap on a spark test tool.

If both of these are good test the fuel pressure on the engine. It should be over 34 PSI when you turn the key on and maintain it when the engine is running. If it does not, you will need to remove and open the VST on the engine to see if there is an issue with the high pressure fuel pump.