1995 Ford F-150 fuel canister in engine compartment overflow

Hi my 1995 Ford F-150 is leaking gas from a small canister down in the lower passenger side of the engine compartment. The canister has two spherical caps on it and two lines coming out of it. One line goes to the engine, while the other goes back towards the fuel tanks. The truck does have the dual fuel tanks but the front tank hasnt worked since I got the truck about a month ago. It is leaking so much fuel that the truck is only getting about 7 to 9 miles to the gallon. Any help you could give me would be very much appreciated