Re: Frustrating boat stalling problem
I agree you need to change the lower cable and possibly your lower shift arm bushings. The easy way to confirm if the interrupt switch is in fact getting tripped is to watch the shift linkage on the engine as someone else shifts into gear. You can do this with the engine on or off. If you see the interrupt switch move from its resting position you can be sure 'something' is binding. (i.e. lower shift cable or the shift arm cannot swing)
Just to explain what's going on, the shift interrupt should only be triggered when you try to take the boat out of gear. Basically an Alpha drive is a 'crash box' so when you pull back on the throttle the shift cable tries to pull the drive out of gear but pulls against some resistance because the clutch dog is engaged and bound up by the resistance of the drive spinning the propeller in the water. So the interrupt switch gets tripped by this resistance and kills the spark to the engine for a split second but it's long enough to free the clutch before the engine dies. If the shift interrupt is getting triggered when trying to go into gear when there should be no binding of the cable imparted by the drive on the clutch then your cable is likely binding all on its own. In this case, even if you could get it into gear, the engine would likely die when you went to take it out of gear since the bound cable might hold the switch on and kill the engine.