Dont water separator filters also filter?
Mine does..
I still have the engine filter on the power head, but only have the water separator/ filter before the bulb pump.
Being only a 9 hp the flow will be very slow compared to say a 150hp V6 and the overall fuel usage over say a yr will only be about 1 day out of the 150 hp.
I dont see any requirement to have possibly a 3rd filter in the system... if anything having to pass thru more filters would load the fuel pump a little. This Could have the potential to limit fuel to the carb/ metering systems under loads.. leaning out.. not good.
Side note.. mount or have the priming bulb pump hanging vertical.. pump upwards. If dont you will find after standing , say fishing, go to fire up the fuel has drained back. If not vertical the little ball bearing in the non return valves fall out of the valve opening it up.