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Charles
Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3844
Experience:  US Navy (Ret) Certified Mercury Marine Tech with over a decade of repair experience.
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My motor will not go over 4K RPM it goes into guardian mode?

Customer Question

My motor will not go over 4K RPM it goes into guardian mode? It does this whether in neutral or drive. Is there an over rev limiter while in neutral and is there a switch that tells the motor that it is in gear to shut off the over rev limiter?
Submitted: 2 years ago.
Category: Boat
Expert:  Charles replied 2 years ago.
Hello, my name is***** you for allowing me to assist you today.
Would you please post the serial number of the engine?
Customer: replied 2 years ago.
1B373135
Customer: replied 2 years ago.
2007 Mercury 115 3 cyl DFI 2 cycle
Expert:  Charles replied 2 years ago.
Thanks,
There is a shift switch on these motors that can fail. When it does the ECU will think that the engine is stills in Neutral and not in gear. This will start to limit the RPM about 2500, but you can still bring it up further. Some times the switch will change positions when the boat is on plane. That would cause you to get an alarm and the engine to slow down.
Customer: replied 2 years ago.
Do you know where the switch is located?
Expert:  Charles replied 2 years ago.
Sure do, it is part 29 in this diagram.
http://www.boats.net/parts/search/Merc2/Mercury/115%20DFI%20%283%20CYL.%29%281.5L%29/1B417702%20THRU%201B736885/Exhaust%20Plate/parts.html

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