merc black max help - The Hull Truth

salvagefirst · 05-26-2009, 05:14 PM

i have a 90 merc 200 hp carb black max that has 2 dead cylinders on the same bank. ,replaced weak batteries,changed filters. can run the boat 20 minutes under load and the cylinders will start firing,115 to 120 compression all cylinders, switched the switchboxes from one bank to another,changed the plugs around,and getting a good blue arc from the plug wires, makes no differance. Whats the possibility of a bad reed valve causing this? Any suggestions would be greatly welcome. Les

A1 Outboard · 05-27-2009, 07:13 AM

If you have bad reed valves you will see fuel spraying from the carb opening when the engine is running. Normally reed valves will not get better after running the engine hard. Try running internal engine cleaner through the carbs when the engine is warm. Use the whole can and then let the engine sit for at least 4 hours. You may have stuck lower rings. These will not show up on a compression test. It may take more than one application to clean up the rings.

salvagefirst · 05-27-2009, 08:47 AM

what type of cleaner would you recomend,something like ringfree or seafoam? Thanks Les

A1 Outboard · 05-28-2009, 07:33 AM

Ring Free is a detergent product that is added to the gas. Bombardier Engine Tuner seems to be the strongest internal engine cleaner on the market. The fuel additive products will keep your engine clean after you use the internal product.

run out · 05-28-2009, 03:13 PM

i had a 97 200 B\Max that was running horrible, compression checked out 130 on all cyl; added star tron fuel additived to a remote tank and before i pulled out of slip motor was purring like a kitten. never stopped useing stuff sinse. put in lawn more, sat all winter and started on first pull. this stuff is great, got a miss out of my buddys 350 chevy truck. is cost a bit but it worth it. might give it a try. i think it is the answer to the e-10 garbage problem we are having. good luck.

run out · 05-28-2009, 03:17 PM

sorry salvage that was a 87 200 black max i had.