2013 Mercury 25hp 4 stroke bogs out at wot

[Dustyhall]

Have a 25hp outboard that bogs when accelerating. Only happens when underload, can run it on muffs in my driveway with no issues. Bogs when approaching wot, then recovers, then bogs again. Fuel pressure is 48-50, new tank, new gas line, changed both filters......am at a loss. I was thinking possibly a stator but can not find the specifications to verify if it is good or bafd. Any help would be appreciated.

 

[EarlyCuyler]

I’ve got the same issue. 25hp Mercury looses power under full load. Runs fine in the driveway.
Wont go over 10mph, sounds like it’s shuddering/knocking at wide open throttle, loosing power.

 

[EarlyCuyler]

I’ve got the same issue. 25hp Mercury looses power under full load. Runs fine in the driveway.
Wont go over 10mph, sounds like it’s shuddering/knocking at wide open throttle, loosing power.

 

[Texasmark]

Running under load requires more fuel and more advanced timing....to help in pulling the engine toward higher rpms.....example was the vacuum advance in autos back in the days of carbs.

You're driving along and need to pass somebody so you stomp on the gas, that opens the butterflies and that vacuum is transmitted to a diaphragm attached to the distributor that moves the timing earlier. Engine accelerates at a faster rate with the load than would otherwise happen. Shuddering is lean mixture under load back when I ran 2 cylinder engines, Like old OMC 2 cylinders coughing and sneezing.