Hey there. I did a water pump on my '84-30hp Evi, got it all done, submerged the lower unit in a cooler of water, electrical taped the top of the driveshaft to my Hitachi 3500 rpm drill, and SLOOOWWLY cranked it up...nothing. I pulled it apart, verified everything was kosher, ran her back up to speed, nothing. I tried several more times, and then suddenly-voila! Water sprayed 6' in the air. I never figured out what the problem was, but it works fine now. (I even verified proper impelller rotation when I installed it, as this is probably the most common error with water pump re-does.) Gooduck with it; it's well worth the effort
This was the key. Its like it had to build pressure, and once it did it worked great from that point on.
Now the pump works, but the motor isn't running right. I am starting a new thread so not too confuse the two separate issues.