if you can unbolt the filter housing from its location and set it aside away from the fan/accessories area without disconnecting the fuel lines i would start there. look over the housing at each connection, you should be able to see signs of leaking fuel from there (if thats where its leaking from). removing the filter housing should also let you see the IP (injection pump). if you can see any signs of the fuel leak, fire the truck up and look in those areas.
