It’s not a short shaft engine. Got it mounted on a typical 14’ bateau (Jon boat).
This is the fifth running fastwin I’ve owned.
OK. But perhaps there is something wrong with the bottom of the boat, or perhaps some marine growth on it causing the interference/engine ventilation. Did you add any transducers or other accessories like that that may be causing an issue?
You have tried a few different props, all give the same issues.
It is possible that the crank/driveshaft splines are wiped out, especially if this is a salt water engine. But, again, I’m not there and can’t hear/see what you can. I don’t want you to rip the powerhead off unless/until you have confirmed this condition. A few other things to look for….
The water pump will stop working if the driveshaft stops spinning (damaged splines). So, perhaps you can tie the boat to the dock, put it in forward and advance the throttle to the point where it messes up. Now look at the water pump discharge. If little or no water discharge is evident, this points to damaged splines. You have tried a few different gearcases, so this would seem to rule out a broken pinion gear or internal driveshaft breakage.
Again, try to post a video of the engine misbehaving for us….
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