1989 Yamaha 40hp 2 stroke water pump

I just bought from a friend a 89 Yamaha 2 stroke that was rebuilt 10 years ago and stored ever since. I ran it for the first time today and it ran perfectly and is way too much power for my 16' aluminum boat. I think I may have a problem, no water comes out of the weep hole under the powerhead when running in the water. But, when I put muffs on the motor and run it in the yard, water comes out of the hole. Obviously I am pressuring the cooling system when running off on my hose. Does this mean the water pump is bad? I am not sure if it was replaced during the rebuild. I ran the boat for almost 2 hours today and it did not overheat, so some cooling must be taking place.

Is the factory service manual the best, or is there a better aftermarket manual? To get to the waterpump, do I have to remove the lower unit?

Thanks!

Chris