Fuel smell through air vents?

I have a 1990 corolla seca. I was getting a fuel smell on and off through the air vents and discovered my fuel pump was weeping slightly around the seam (mechanical type driven off cam) I stopped the leak with some epoxy fuel tank repair stuff. Seemed good for a couple of weeks but now the smell is back worse than ever. The smell is so strong you'd think my air vents were full of fuel. Pump doesn't seem to be leaking and I can't find a leak anywhere else, carby, lines etc, nothing. What could it be?