'89 searay/merc 100 wont fire

tomandkit

Recruit
Joined
Jul 31, 2007
Messages
4
I have an '89 searay with a mercury 100 outboard. It won't fire. we changed the plugs because they were filled with oil and that worked for awhile, now same problem and the bottom plug is covered with oil. Suggestions?
 

Laddies

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Joined
Sep 10, 2004
Messages
12,218
Re: '89 searay/merc 100 wont fire

Ck it for spark on all cyls. It probably don't have any if thats the case disconnect the black/yellow wire at the switchbox, if you still have no spark test the stator
 

tomandkit

Recruit
Joined
Jul 31, 2007
Messages
4
Re: '89 searay/merc 100 wont fire

I checked for spark and am getting spark on all 4. The bottom plug gets oily, I took it out this morning , cleaned it and nothing, Tonight we went out, put in an old plug and the thing started! What the heck?
 

Laddies

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Sep 10, 2004
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12,218
Re: '89 searay/merc 100 wont fire

Are you useing the right plugs? When idleing remember that engine is only running on the top 2 cyls.
 

tomandkit

Recruit
Joined
Jul 31, 2007
Messages
4
Re: '89 searay/merc 100 wont fire

Yes, we are using the right plugs according to the boat shop. They looked it up just to be sure. Any ideas why just the bottom plug keeps fouling?
 
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