Merc bogging out under medium to heavy throttle????

[BigAl1]

Hey fellas, I have another problem with my merc 1986, 115. The Motor runs great at idle, low speeds, but under full throttle it bogs down to 1/3 to 1/2 normal speed. Any ideas?

Thanks
Big Al

 

[Chris1956]

Re: Merc bogging out under medium to heavy throttle????

sounds like fuel delivery issue. Pump the primer bulb and see if bog goes away. If so, make sure filters and antisiphon valve are clean, and rebuild fuel pump.

If that is not issue, check spark on all cylinders. Make sure you still have spark as you push the throttle forward.