It might help to remove the fuel pump and siphon it out from the top. Then repair the tank, because a rusty filler neck has probably let water in.
Once you've siphoned all the crap out, put a bit of fresh fuel in the tank, temporarily disconnect the fuel feed at the engine, then run the fuel pump to flush the water out of the lines. Then reconnect the fuel feed at the engine and run the engine for a bit. Then siphon the fuel out of the tank to get rid of the water that will have been flushed out of the return line. Finally, replace the fuel filter. A can of fuel line antifreeze in a tank of fresh fuel should absorb any remaining water.