1985 merc tower of power 115 stumbles on throttle

[boydog]

my 115 will stumble and stall if i try to give it throttle all at once, if i give it a little at time, i can feel it start to pick up and then it takes off and runs perfect. i can stop and fish and the same will happen again. carbs have been cleaned professionally, im guessing fuel pump losing pressure at idle maybe and then at wot all is good. what do you guys think?

 

[racerone]

Open the low speed mixture needles 1/8th turn at a time.---Test run again.-----That simple procedure often fixes that issue.

 

[jimmbo]

I had a 1984 115, and the moment I would hook a ski rope to the boat the engine would do the bog and stall, unhook the ski rope and it would run fine. The dealer, after many phone calls to the Mercury Service Rep, finally fixed the problem by adjusting the Primary Pickup quite a ways from spec

 

[boydog]

will try tomorrow and report!

 

[boydog]

not to sound stupid, but which is the low speed needle

 

[Chris1956]

There is only one needle on each carb. On a sidebowl carb, it is aprox. at the 2 o'clock position. It is the Idle speed mixture adjustment. Opening the needle richens the mixture to two cylinders, fed by that carb.