Why would 1998 harley Davidson electro-glide leak gas from the back hose that goes from tank to fuel injector system?

i had the same issue some time back on a 98 Road King Classic. Ended up being the back flow preventer between the fuel line and the tank. i fixed my by removing the fuel line on the left side of the tank. this is very easy. move the hose out of the way. now the fun part. the back flow preventer screws into the tank. it can be accessed after the fuel line has been removed as described above. the leak could be coming from the seal on the backflow preventer or it may just need to be tightened. there is a special tool that can be purchased from harley but i made a tool by taking wood chisel and grinding the edges down to fit the slot in the backflow preventer (bp). be very careful not to compromise the threads for the fuel line. i took the bp out, put a new seal and then used some thread sealer. tighten the bp up, reinstall the fuel line and hope for the best. hope this helps. greg