Originally Posted by bobc
I was concerned about that problem, but now believe that my tanks are reasonably clean. The return is at the top of the tank and on the other end. When the tanks were less than half full, I emptied one into the other and then added back in a very small amount of fuel, just enough to keep the polishing pump primed. The fuel would drop from the top of the tank to the bottom with some velocity, and then stream down to the other end. I figured that would knock something loose, but it didn't. Other than a couple of specs of gunk, the fuel came out clean.
The boat we serviced in the picture was in the process of a twin Diesel re power, The owner had run his fuel polisher often and his fuel was spotless when we pumped the 300 gals into our truck, The outfit doing the re power recommended to the owner to clean his tanks @ this point due to a high pressure common rail system with the new diesels, We had real poor tank access thru a fuel sender and we were not really expecting that much sludge do to the polisher and the above average polisher installation and the fact the owner said he never had any fuel problems in the past, We pulled fuel from his low point valve @ the polisher input and snaked a 1 inch wand thru the open fuel sender and pressure sprayed the best we could, The tank builder did not recommend we install a inspection plate due to to the wall thickness of the tank skin, the tank had 3 sections and we spent 1 hr in each section snaking past the baffles, This is not the best way to clean a fuel tank but some times that all you can do with out pulling the tank or cutting up the boat, The boat was on the hard & I really cranked up the fuel pressure for this tank, I took the picture because the owner was not there for the cleaning and was concerned about waisting money for the service, He has now scheduled another tank cleaning @ the next haul out. I find on most fuel related engine brake downs the owners felt the tanks were clean enough for normal operation and were surprised @ the volume of sludge we removed.