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Charles
Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3342
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: 1 year ago.
Category: Boat
Expert:  Charles replied 1 year 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 1 year ago.
1B373135
Customer: replied 1 year ago.
2007 Mercury 115 3 cyl DFI 2 cycle
Expert:  Charles replied 1 year 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 1 year ago.
Do you know where the switch is located?
Expert:  Charles replied 1 year 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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