Well, first things first buddy, gotta tend to the overheat?  How strong is the water outlet under the pan, good stream?  Perhaps just the thermostat?

Having to pump the fuel bulb constantly usually means the fuel pump is weak, but not necessarily!  Perhaps there is an air leak somewhere in the fuel lines leading to the fuel pump.  Or, perhaps there is debris in the filter/tank/problem with tank pick up/vent.

Do you have another tank to try?  Please do NOT rip apart that fuel pump, getting it back together properly is very tough, and new ones are very expensive.

short shaft  engine on a long shaft transom ??        upper – lower  water  tube grommets   all in place  ?   does water pour out the rear end  or trickle ??

salty engine or fresh water  ??    did you ever pull the cyl head to inspect  jackets ??

Is anything coming out of the water discharge?  If not, perhaps you didn’t get the water tube lined up/inserted correctly into the water pump.  Is this a new thread, or a continuation of an older one?