Checked compression today on 2000 Merc EFI after engine running rough over the weekend. Compression 135 PSI on 5 cylinders +\- 5. Compression on 6th cylinder only 65 PSI. Spark plug has metal residue on it. Checked fuel injector for that cylinder and it was dead. Engine ran lean. My question is can I rebuild one cylinder or does entire engine require tear down? I know that the best way to go is to rebuild entire engine, but that is not a viable option at this time due to finances, I plan on buying a smaller boat with smaller engine next year (4 stroke for trolling) and do not want to sink a ton of money into this one. Does any one have a guessimate on labor hours for the job or cost? I can pull powerhead and strip parts off of engine to reduce cost. I have done rebuilds on car engines but, I believe that an outboard rebuild is beyond my capabilities.