I cant seem to exactly pinpoint it. It is coming from the rear driver side corner of the block and only when im driving. When I stop the fuel that has been sprayed all over the place drips off the tranny. I just happen to see a small trail coming down the side of the block and think this is where its coming from. Is this a common thing. Truck hasnt lost any power or running differently. Yesterday it was pouring out but dark and I couldnt see anything. Please help. How do I get to it? Pics would be helpfull.

 

sounds too me like it's coming from one of the back injector lines....... Or it could be coming from the fuel fuel line where it turns from a hard line along the frame to a rubber hose to the filter canister...............

 

I cant find any fuel laying up by the injector lines but it has sprayed a bit up onto the bottom of the cowling.