98 250 Ox66 Problems

[bayrat27]

Hey Guys, new to the forum. Havimg some issues with my yamaha and thought I'd have youguys take a look at what I found. As the boat is running it will sputter, n ot bog down but just kind of hicup when its running, ususally happens over 18 -19 knots. Filters are all clean. I noticed in the first attachment that the lower part of this covera was cracked and that a screw fell out of it, found it in the bottom of the motor. Also, notice alot of salt deposit on the starbord topplug. Any thoughts would be appreciated. Vito

[rodbolt17]

will run perfect even if that cover was missing.
have you tested spark plug cap resistance? engine compression?
spark?
O2 sensor output voltage?
fuel rail pressure at the problem RPM and load?