Our old Rule 1500 bilge pump was not working very well. It would often spin but not pump. The first issue I found was that it had a check valve installed just after the pump. It was sticking and restringing the flow. Since the Rule manual specifically says to NOT use a check valve, I removed it. That helped for a while, but as the pump aged, it more and more often would refuse to prime and pump.
The original setup uses a flimsy corrugated hose, which is prone to cracking and adds a lot of friction to the system. It also runs directly to the through-hull on the transom, which is higher than the pump. With this setup, in following seas, it could create a siphon that could flood the boat. Also, when the pump stopped, all of the water in the entire 20+ feet of hose would run back into the bilge.
When it came time to replace the pump, I decided to address all of theses problems by installing a larger 2000 gph pump, stronger smooth-bore hose, and an anti-siphon loop under the galley sink.
Now we get good solid flow every time, and only a small amount of backflow (from the loop to the pump).
I even put the dock hose into the bilge running at full, and the pump was able to keep up with it.
The main issue is that the drain holes between bilge compartments are not big enough to allow the full flow rate to get to the pump, so it has to shut off for a short time until the water flows into its compartment.
Also, the float switch is flakey and eventually needed to be replaced.
