You didn't say how long it sat up, but I have sat up diesels for years with no fuel problems after putting back in service. If you suspect an algae problem, just dump in some biogard.

I put a Ford diesel tractor back in service this past summer that had sat for some five years. I put a fresh battery in, checked the oil and it started up after the starter rotated the engine less than one full turn. It was amazing. The tank was half empty, so I filled it up with fresh fuel and changed both fuel filters.

Just because it sat up does not mean that you necessarily have an algae, or any other fuel contamination problem.

As I said in my previous post, this stuff is not like gasoline.

Happy New Year,