If it were me put some good dry gas to how many gallons of gas you think in the tank. Then keep some extra filters on board and see if it better. If it dont get better than pump the tank.
you have to have the right setting tell it what transducer u have fishing mode shallow water palatte no. 1 sensentity auto +2 u want a dirty screen anymore more questions call me 585-409-7294 jeff.