Minnesota started a 2% bio requirement in 2005 and 5% bio in 2009. There was a suspension of the requirement during the winter of 2005/2006 because of fuel filter plugging (determined to be caused by poor quality control in the bio diesel) and again in the winter of 2009/2010, also due to filter plugging. I was running a test fleet of off-highway equipment in the winter of 2005/2006 and experienced a lot of plugging - operators complained of lack of power and we found the filters coated with a black sludge. We had the crud analyzed and discovered we had crappy fuel. The supplier insisted the fuel we were getting was good so we checked our storage tank - water and sludge filled the bottom. We had neglected to maintain our storage properly. Long before bio diesel came around we had algae problems. When I worked at Allis-Chalmers from 1967 - 1989 we had continual reports from customers about engine problems due to algae in the diesel, and same thing when I worked at Case IH from 1989 - 1992. In fact during the summer of 1991 at Case we drained and cleaned our diesel tank and found holes rusted through - we were getting water in our diesel at the factory and starting the problem right there. So algae in fuel isn't a problem that started with bio although bio may have made things worse for people who have water in their fuel. Something that has made engines more sensitive to algae is finer filtration that has come in with newer filters required to protect the latest injection systems. The old Roosa-Master injection pumps had peak pressures no more than 6,700 psi while a new common rail system can be over 30,000 psi. At those pressures the fuel needs to be super clean to prevent excess wear. When my outfit changed from Stanadyne (formerly Roosa-Master) pumps to common rail the filtration used on the old system would result in injector wear-out in as little as 50 hours. The new filters we developed did the job protecting injectors but dirty fuel or fuel with algae can plug the new filters darn quick.
