I have a 1991 XJ6 vanden plas that wont run right, and stalls when you try to drive it. I have checked the fuel pressure and its only got 30 psi and I am told it needs 42psi. So I am assuming I need a new fuel pump, but I was told that the car has 2 fuel pumps, one external and one internal but I have also found info saying it doesnt. I cant find or hear the external one if it has one, but I do hear the internal. Would the problem be fuel pump?

I have changed the mass air flow meter, fuel pressure regulator, fuel filter, dristribiator cap and rotor, and spark plugs.