98 Escort won't fire, fuel starvation?

Have a 98 16 Zetec Escort, been stood for a while, turns over well but does not fire due to fuel starvation. Electric fuel pump does not start before ignition as it should. RAC man says that pump at tank end is clogged cos been standing. Planning to remove tank and clean tomorrow, what should I use to clean and is there a test to make sure that this is problem before removing tank?