mariner 150 v6 problems

[jamyb]

Hi all newbee needing help. I have a 1989 mariner 150 v6 that when is in gear will only reach 2000 rpm but when out of gear will reach full rpm any ideas all carbs have been cleaned and fine fuel hoses fine and fuel conetions are good and just had a full service. Any advice will be much appreciated

 

[Barramundi NQ]

Hello jamyb
Did you replace the fuel filter at last service? Do the carbs open fully when you try it by hand on the engine? Is the fuel fresh?

 

[bilge rat jim]

On a 25 year old outboard, you may want to start with a compression test.

 

[jamyb]

Thanks for the replys. Its brand new fuel carbs open perfect and yes its had a new fuel filter it baffles me

 

[Barramundi NQ]

Is one or 2 of the sparks wet

 

[Dukedog]

If motor is running smooth, not spitting, sputtering, generally runnin' rough, just not turnin' up with a load on it start with stator check out (resistance and DVA). Fire at all 6. Comp check for peace of mind........

 

[jamyb]

All sparks are dry and compresion is good on all

 

[Woody47]

I have a1979 merc outboard 3 cylinder, similar problem bogs under load. As I excelerate I tap on the choke button until it's wide open. We also took off the cover from the carbs, put hand on them one of them at a time to cause a vacuum, i think it helped. My next move is to spray a small shot of carb cleaner in each carb? Does this sound like a good idea, anyone?? Thanks

 

[Barramundi NQ]

Hi jamyb, have been able to check the quality of the spark on each cylinder?

 

[enginepower]

A buddy of mine had a similar problem. The 2 top cylinders were dead. Spark and compression good so it had to be fuel. Removed carb and found the needle seat wasn't tightened from a prior rebuild and it backed it's way out and jammed needle into it so very little fuel was getting in carb if any.