Problems with 2003 optimax 225

Hello Folks, I just launched the boat two days ago after a two week break and when I tried to fire up the motor it refused to start, I did the cold start procedure and it started but it's now running on three cylinders. I cleaned the fuel pump but the condition remains. There is spark on the spark plugs on the port side fuel rail but no operation on all six cylinders, what r the likely cause(s)? Thanks

 

Sorry, one correction it's the starboard side fuel cylinders that have the problem

 

Thanks to all who were doing some research or even pondering a response, I got the problem corrected. I replaced the computer and everything is good now. Thanks again