if your going to replace the fuel filter and go thru all the work of pulling out the check valves,i would most likley replace them,they can get clogged and have serious pressure issues with fuel,causing serious drivability issues,there cheap enough get new copper crush washers and definatley replace both check valves.

__________________
enjoy life,take the coal that is handed to you and turn it into diamonds. { PHILLIPIANS 4:13}