BIG QUESTION --- How "old" is the fuel?? If it's more then 2 years, then you'll need to do a VERY GOOD JOB of cleaning the tank. I just went through this process. I added a product called Seafoam to help clean out any crud that had accumulated and after towing the boat around for about an 1hr on the trailer, I raised the trailer tounge as high as possible and then removed the fuel guage sender(s) and pumped out all of the old fuel. Caution here --- Only remove the sender if the tank level is lower than 1/2 the capacity. I used a 3/4' piece of PVC and ran a 3/8" line thru it so I could control where the tube was pointed. You wouldn't believe the CRUD that came out. Be sure to have at least 2-3 extra filters available for each engine after you have re-filled the tank and started to test out the fuel system. You may even consider only filling the tank(s) 1/2 to 3/4 in case you need to go back in thru the sender hole again.
Run the engine(s) for about 5-10 minutes and then remove the filters and check for water by dumping then into a LARGE plastic bag so you can see any water. Repeat this process until your happy that you've removed all the water and crud.
Good Luck!
