merc 150hp no idle when warm

bmmc

Idles fine cold,when warmed up will not idle.

Rockslam

Need some more information to be able to help. What year? Carbed or Fuel Injection? 2-Stroke or 4-Stroke?

bmmc

1972 carbed,2 stroke

Alex from GA

Boy that's older than my '74 850. You might be better served going to johnsoldmercurysite.com.

bmmc

sorry the year is 2002 not 1972,my bad.

leonreno

There is thermal check valve on starboard head between bottom two spark plugs with a hose going to the carbs. It opens and closes depending on motor temp to enrich fuel when cold for better idle when cold. If it sticks then it will also enrichen fuel when warm and cause bad idle due to it running too rich. I would check it first, it's cheap and easy to replace.