1999 Suzuki 9.9 keeps fouling plugs

DeanHensler

Petty Officer 3rd Class
Joined
Feb 14, 2013
Messages
82
If I put brand new plugs in, it runs well for about 5 minutes. After that it drops power by about 50%, then eventually it will die and won't start anymore. Put new plugs in and it runs again for another 5 minutes and repeat...

The plugs are fouled really bad. Like covered on coal.

Any idea what might be causing this?
 

DeanHensler

Petty Officer 3rd Class
Joined
Feb 14, 2013
Messages
82
4 stroke. Unsure of number of hours. I did a compression check and it was 90 on one cylinder and 100 on the other. Both cylinders foul the plugs equally.
 
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