I lost what I suspected was the impeller as you can see. I replaced it and removed the hose to the intake side of heat exchanger and got a few rubber pieces out but no where near the amount that is missing. I started the generator with the hose removed and had good flow. Put the hose back on and get no flow out the side of the boat and the generator shuts down (which is good to know). I tried to run a water hose in the exhaust to back flush the blockage but it didn't work at all.
Now I can't get down thru the narrow hatch to get to the heat exchanger without removing the exhaust tube from the port engine. Has anyone had a similar problem and fixed it without ripping everything apart ?