Seems like the symptoms of a pressure leak somewhere - shouldn't need to
pump that many times to reach a sufficient vacuum for only a one-gal container. I'm not very familiar with the WM version, but I have had two different types of oil
pumps with prior boats - both relying upon a vacuum.
The first one was a royal pain - dip-stick hose connected to a steel container with a cylinder
pump attached to the cap. It never really sealed well due to a bad O-ring at the cap. I replaced the gasket and it worked well for a while. Finally replaced it with a Tempo Oil Boy:
Well engineered and built - the
pump worked very well - but I don't need it any more since my current boat has an integrated oil
pump. It's only a 5 Qt capacity, but draws oil after just a few
pumps - fills with warm oil in about 10 minutes.
Check all the rubber seals on the input and putput caps, as well as the
pump seals. Could also be the cap is cross-threaded.