I discovered a fuel leak from here. What can cause this besides a bad gasket. Thanks.

 

I'd start with swapping the gasket (assuming that there is one) and go from there....

Don't drive, while the fuel is leaking... - or alternatively always take some sausages and long sticks along with you for a BBQ on the roadside...

 

Fuel leak on top of any engine equals do not drive

Alot of early Jaguars suffered the fate of a smoking hole in ground

You can leak check it by jumpiring the hot at all times # 1 fuel pump relay and plenty of the cheapest kitty litter to keep fuel away from truck area or a hill

Pin 3 ( hot at all times ) to 5 ( to fuel pump )

Use medium gauge wire with blade type wire ends , the auto parts store can make one for you

 

Is it in the fuel pressure regulator?

 

X100, X308 - Fuel Pressure Regulator - (NCA3007CA)