Fuel Filters
Depends on how big a mess you mean! First, close the valve at the fuel tank. Then drain the bowl into an old container (peanut butter or even a soda plastic bottle). Put paper towels or other catch-it stuff below, and unscrew the filter. Have somewhere to put the filter once it's off.Don't forget to check the filter inside the electric fuel pump. Many Catalinas came with the fuel pump first and then the filter. The filter should be first. Easy to repipe.You didn't mention what engine you have. If it's the M25, the secondary filter on the engine is easy since it's screwed on top up, shouldn't leak a drop.Follow the instructions on the filters, like putting oil on the seals before you replace the new ones.Bleeding is easy -I put it off too long for fear. Once you replace the filters, open the fuel tank valve. Just loosen the vent screw on the Racor first, turn on the engine key to get the electric fuel pump running (but don't turn over the engine) and this will fill up the Racor. The loosen the bleed screw on the secondary filter on the engine, until you get fuel and tighten. Finally, loosen the thumbscrew air bleed at the injectors and you're done.