Gas leaking from gas cap??

[87 HJ60]

I recently replaced my leaky fuel tank with a decent used one. After my first full fuel up I noticed that there was fuel residue on the fender just below the fuel filler door. At first I thought that I overfilled but even when the tank is just half full there still is fuel leaking out on to the fender. The amount that leaks out is not a lot but it is enough to leak a fuel residue streak on the fender.
This never happened before I swapped fuel tanks. My truck is a 1987 HJ60 and the replacement fuel tank also came from a 1987 HJ60. All the vent lines were hoooked up and the "evaporative separator" has been replaced about a year ago.
There is another thread about a FJ60 with excessive pressure in the fuel tank however that's not the case in my situation. When I remove the gas cap there is no hissing or fuel spewwing out.
Can my problem be caused by somehting simple as a faulty gas cap gasket? As I mentioned, this problem only started happening after replacing the fuel tank.

 

[doug720]

I have seen some filler neck pipes that have had the "threads" that the gas cap screws onto bent up. This happens from the gas nozzles being push down hard and bending the threads. You can straighten them fairly easily to get the cap to close tight.

Can't hurt to check.

Doug

 

[import silvia]

I had this issue on my 62, it was the threads as Doug speculated. I bought a locking gas cap and the 4 points of contact it provided were sufficient to keep the gas inside the tank.