Fuel tanks dirty

[Rawze]

you could always send a sample off to a lab and let them determine what it is.

You also do know that CM570's, CM870's, and Cm871's are known to make asphaltine in the return lines right?... especially if there is a higher bio-blend diesel used (above B7). Look at the fuel pump when you fuel. It should show the "B" rating of the fuel.

That is why you use a 7 or 10 micron filter in your davco to help keep it at bay.

and the best way to prevent algea buildup is to always fill the tanks to mostly full each day, so that they cannot sweat on the insides of the tanks in rainy/cold weather (same as when your windshield fogs up).