I have a 97 Jaguar XJ6. When the car is driven for a hour or so and truned turn off for less than a hour when I get back in the car to start the car it will not start. There is a very strong gas smell in the engine compartment. The engine will trun over but the engine will not start. I have replaced the battery. The problem only seems to happen when the car has been driven more than a half hour. If I let the car sit for 1 hour the car will start but there is a black smoke that comes out of the tail pipe. I have taken the car to my local technician and the car will not act up with him. He tells me that he can not find anything wrong with the car. There are some engine codes that the technician was able to get out of the computer : PO116 PO125 PO118. He tells me that these codes have nothing to do with the problem. Please help