Yes, you can have the tank''s fuel cleaned (or ''polished'') but I don''t think that''s your problem.
Have you replaced the primary fuel filter (the one mounted on the engine, not the fuel filter/separator thru which the fuel first passes when leaving the tank)?
What age is your boat? Until the 90''s, many boats came with tanks built with the pick-up tube (which feeds your fuel line enroute your engine) with a mesh screen over the tube. Over many years, particles can easily fill this mesh screen (or nearly so) and either stop the engine totally or make the little diaphram fuel pump work oh-so-hard to get not quite enough fuel. You should be able remove the fuel line at the secondary fuel filter/water separator, slip on a dual barb fitting and a short piece of clean vinyl hose and then blow backwards into the tank, feeling steady backpressure due to the head pressure of the fuel in the tank. You should hear it gurgling. (You did check your fuel shut off valve to make sure it''s open all the way, right?) If you can''t do that, it''s time to get out the dinghy pump, build up an adapter that allows you to connect the pump hose to the fuel line, and then push via air the crud off/out of the mesh screen in the tank. (You may also be able to pull the pick-up tube to check it, but often this isn''t possible without first removing the tank).
I once had to construct a completely new fuel supply from an old tank to my Racors when the tank''s pick-up tube screen filled up; it was offshore at night and it wasn''t fun. I didn''t think of the dinghy pump idea until after I''d confirmed it was the pick-up tube that was the problem...wished I''d thought of that earlier in the process!
Let us know how it goes, and hopefully there''ll be other suggestions along with this one.