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Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3315
Experience:  US Navy (Ret) Certified Mercury Marine Tech with over a decade of repair experience.
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I have 2007 mercury outboard 90 hp will idle till gets warm

Customer Question

i have 2007 mercury outboard 90 hp will idle till gets warm then starts to run eradict at low rpms runs ok at high rpms it is a fourstroke
Submitted: 2 months ago.
Category: Boat
Expert:  Charles replied 2 months ago.

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

This is sounding like you have a failed MAP reference hose inside the FSM. this will allow extra fuel to enter the intake and cause a rough idle, but will run fine at speed. To repair this, you would need to remove the FSM from the engine, open it up, then replace the hose.

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