What is your actual precise model/serial? In 2005, one would expect that you may have a 30B, which is an EFI motor.
If you instead have the
What matt.speedtriple said!
There is an EXCELLENT Honda carb repair manual that you can buy for around $35 to $40 if you haven't done this
Forgot to mention that you ought to go to the Merccruiser forum on this site. Go to the top of this page, click on "Forum Home" at the top right,
Complicated is relative. To me, I would not tackle it without the shop manual. Plus, you need to find those check valves and make sure they are working