What does fail fuel 66 mean in your 1993 xj6?
The fail fuel 66 message in your 1993 XJ6 indicates a problem with the car's fuel system. The most likely cause is a failed fuel pump, which is responsible for delivering fuel from the fuel tank to the engine. To troubleshoot the problem, you can check the fuel pressure at the fuel rail, which should be around 35-50 psi. If the fuel pressure is low, you may need to replace the fuel pump or the fuel filter. You should also check the fuel lines for any leaks or blockages.