Spark plugs or carb?

[VaRick]

Alright guys, I need some help. I have a 2002 ProLine 22 Walk powered by a 2002 200 HP Mercury V6 outboard (Carbed). I am experiencing an inability to reach full speed and max rpms. The boat is also very sluggish getting on plane, The last time I went out I was able to reach 23 mph, but could not get it above 4200 rpms. I figured it might be bad gas or water in the gas so I ran it off of a portable tank with fresh gas, but it did not help at all. I also noticed I was burning gas like crazy, maybe a mile per gallon if that. I am now thinking it may be the carbs or spark plugs. Any ideas will be greatly appreciated. Thanks.

 

[Dukedog]

cdm... maybe one or more..or other 'lectrics... justa educated guess ona computer... could be fuel? carbs or other fuel delivery items also... but cdms are a common problem with 'em.

 

[Chris1956]

Those motors have a fuel pump diaghram that can leak fuel into the crankcase, fouling the spark plugs. What do the spark plugs look like? What is compression and do you have spark on all 6 cylinders?