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Charles, Marine Mechanic
Category: Boat
Satisfied Customers: 3929
Experience:  US Navy (Ret) Certified Mercury Marine Tech with over a decade of repair experience.
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I have a 2007 optimax 115 the #3 plug keeps fouling out.

Customer Question

I have a 2007 optimax 115 the #3 plug keeps fouling out. Motor still runs fine but lacks power. I replace the plug and it does fine for a few times out and then does it again.
Submitted: 1 year ago.
Category: Boat
Expert:  Charles replied 1 year ago.

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

When the motor fouls the plug, is it carbon fouled or wet fouled?

Customer: replied 1 year ago.
It is a dry foul. the plug is black
Expert:  Charles replied 1 year ago.


I take it that the plug is totally black when you take it out?

Do you do allot of ideling?

What oil are you using?

Customer: replied 1 year ago.
Not to much ideling, I use quicksilver premium. Yes it is black.
Expert:  Charles replied 1 year ago.

The motor actually calls for Premium plus oil.

Can you loosen the fuel rail off the studs and then have a helper turn the key on. Watch to see if any fuel is coming from the fuel injector as the pumps run.

Customer: replied 1 year ago.
there is fuel. When I replace the plug it will run fine a few times out then it will start to loose take off power till I replace the plug again. could it be the coil pack getting week?
Expert:  Charles replied 1 year ago.

You had fuel come out the rail with just the key on and not cranking the engine? Was it only on the bottom cylinder?