Notice:
The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.
You either have to prime the pump or try pumping it really fast untill it primes itself. A section of tygon tube sliped over the sink faucet works for back filling the pump with a cup of water.
A couple things come to mind regarding your hand pump not pumping. One: there might be a clog in the hose between your water tank and the pump. Catalina used the Whale pump for most of the production run. That pump is self-priming. So, it might be a build up of crud from water sitting in the system for a long period of time. Or, might be a plugged up in line filter. Maybe even a kinked line.
Or Two: Your pump's mechanism may have just worn out after all these years. West Marine and other chandlers usually sell repair kits for the pumps - usually less than $25.
In addition to what Bill said, the water line may be broken, which won't allow the proper vacuum to build up for the Whale pump to self-prime.
To check any problems with the line, you might try disconnecting the water line from the bottom of the pump by loosening the hose clamp (taking the teak door off, frame and all, helps provide more room to get in there). Then lower the tube to below the water line in the water tank. If water drains well from the end of the tube, then the problem probably lies in the pump itself. If it doesn't drain well, simply replace the line.
Notice: The advice given on this site is based upon individual or quoted experience, yours may differ. The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.