1999 Suzuki 9.9 keeps fouling plugs

[DeanHensler]

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?

 

[Sea Rider]

The plugs are fouled really bad. Like covered on coal. Any idea what might be causing this?

It's a 2 or 4 strokes motor, with low or high hours use ?

Happy Boating

 

[DeanHensler]

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.