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Dominick
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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I have a 2011 Yam 4-stroke F40ELHA. It is ideling too low

Customer Question

I have a 2011 Yam 4-stroke F40ELHA. It is ideling too low and missfiring. The higer t RPM the worse it missfires. Have replaced plugs, changed fuel, cleaned VST tank. What am I missing?
Submitted: 1 year ago.
Category: Boat
Customer: replied 1 year ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  Jason replied 1 year ago.

Hello my name is ***** ***** am I speaking with?

Have you checked compression and fuel pressure? How old is the fuel iteself, and have you run it off of a different tank? What is the story behind the engine, when did it last run correctly?

Customer: replied 1 year ago.
Ran motor off of our shop tank with no results. Compression @ Leak Down fine. Fuel Pres ok. It idles fine but when RPM goes up so does missfire.
Expert:  Jason replied 1 year ago.

Can you tell me what your compression and fuel pressures actually are, the numbers?

Expert:  Jason replied 1 year ago.

Also, I do not know your level of expertise. Are a shop, dealer, or a backyard guy? Have you done a cylinder drop test to try to find the misfire, or plug the engine into YDS?