Have Boat Questions? Ask a Boat Repair Expert.
Hello. My name is Tan. Put fuel with ethanol in the tank and let is sit for a few days this will soften the old fuel. The ethanol acts like a solvent and will dissolve old fuel residue. If you can slosh the fuel around this will help also. I would let the fresh fuel sit in the tank for awhile to let it break up the pold fuel residue. After it has sat for awhile pump tank and inspect. If still dirty repeat the process.
If the tank has rust in the tank don't bother cleaning just replace the tank.
Does this make sense?