[Sans Peur]

What type of pump was it. Most gray and black water pumps are maceration pumps (especially black water). On my old 41 the gray water had a tank with two of the large T Series discharge pumps while the black water tank used one.
On a different boat it used the shurflo maceration pump.

I know my gray water pumps worked off a float switch in the holding tank while every boat I have owned had a dedicated breaker for the black water pump.