Could anyone tell me if the 1992 xj6 3.2 has a fuel cut off switch, if so where.

My problem is that when my jag is parked on a slope it takes a long while to fire up and I have to pump the gas pedal a lot. That is until today when it was parked level....... and now it barely fires and not enough to get the car started.

Maybe it is something else but having read an earlier post it sounds like this could be my problem.