Cummins 5.9 12 valve mechanical expert

[KRatcliff]

Originally Posted by rseibenick

KRatcliff, thanks for the reply. I assume that the Algae problem flares up after I drive for a few hours and the fuel heats up , then I put more of a load on the filtration going up the hills. No issues on level ground or down hill.

It may be that or the filter is just letting enough fuel to flow that you don't notice the lack of power on level ground. The heat may make a difference, but checking the fuel filter would be the first place I would look.