Mercury 150 blackmax wont run over 2k rpm in water

[JamMan]

Hi, i have a 150 Mercury Blackmax 1996 2.0L v6 on a 18ft ring. The first time i took it out it ran sweet had no problems and easily got 55mph.

After this i then took the carbs off and got cleaned, took the oil pump off And run pre mix instead, new spark plugs, new thermostats etc. Put the carbs back together and on the boat ready to go.

Took the boat out after All of this and it wouldnt even go over 2000rpm. When you put your foot flat on the floor instead of accelerating hard it just bogs down and either stalls or sounds like it is struggling.

After this i got a new fuel filter and tryed again the next day, it was a little better would get on the plane but still didnt feel like it did the first time and the acceleration was not there.

Next, i put in all new fuel line and clamps thinking possibly the bad quallity fuel line before could have kinked, perished restricting the fuel flow. Then took it out and wouldnt get over 2000rpm again!

I cant think of much more it could be and it was running perfect the first time i used it and just want to find the problem as im sure it must be something silly.

 

[Chris1956]

Well since you worked on the carbs, I would suspect carb idle mixture settings or link and synch.

You want to adjust all six throttle plates to open at the same time, and open at 8-10* ATDC timing. Max ign timing is 21*BTDC. Disconnect the idle stabilizer.

You want to adjust the idle mixtures for smoothest running, and then richen all needles evenly, (if necessary) to allow acceleration.