The gas tank is held on by two brackets and six bolts. It's fairly easy to drop but disconnecting all of the line tank lines is a pain. Like Dub said, avoid smoking.
Before dropping the gas tank, I would pull the fuel filter and have a friend turn the ign. while you have the fuel line aimed toward a bucket or something. Then you'll be absolutely sure the pump is out and it's not a plugged line closer to the engine.
who said i had friends? kidding - good idea i'll try this asap - geesh there are a lot of lines going to the tank - if i do have to take it down do i need to drop it all the way or do you think i can just sort of angle it to get to the pump assembly?