Please help with my Merc Issues!!!

[1BadTitan]

I have an 85 Merc BlackMax 150. It idles perfect on the trailer all dayat about 1100rpm. As soon as I put her in the water, the idle drops to 400-500, starts to lobe and stalls. Also, when I'm cruising out of the no wake zone, (about 10mins) it seems to load up and bog, but as soon as I tilt the motor up some, I can get it to rev up and go. Sorry if I'm all over the place here, but I cant figure it out and am about frustrated at this point.

 

[spareparts]

star with spark check and compression test, if that's good, go to the carburetors

 

[1BadTitan]

I have spark at all 6 plugs. Good compression all around too. My next stop was the carbs, wanted to check here first.

 

[spareparts]

if you haven't had the carbs gone thru in three or four years, they are probably due. replace the fuel lines and check the fuel pump diaphragm as well

 

[steplift20]

could be the stator, mine had to be replaced about 4 times and when the engine warms up thats when the problem started, but they all are differant have the stator checked

 

[captpete13]

It sounds like the motor is running rich. Especially when you said it runs better when trimmed up. Check the fuel pump and make sure its leaking back into the crankcase. Then adjust the mixture screws. I would lean them out a bit.