I've had the carbs off,now putting them back on.Why would the previous owner have had the main fuel hose going from the RES nipple to the main fuel (T)? 

The two hoses off the bottom of the tank both went to the left inlets on the petcock.

Were they trying to get by a screwed up petcock? I can't remember if it was running on PRI or ON,but I never let the tank get below half anyway....never had any fuel problems.Thank's Ronin

Sounds like the petcock has a bad vacuum diaphram.Tri this if you have 89-01. http://gstwins.com/gsboard/index.php?topic=19363.0

Thank's Ben..

You're welcome.