Code fuel 1 would indicate Oxygen sensor. A good information source is the Haynes Manual Jaguar XJ6 1988-94. Good luck.
Code 43 is a problem in the fuel delivery system.
The fuel fail 89 VCM code on a 1990 Jaguar XJ6 indicates a problem with the vehicle's fuel management system, typically related to the Vehicle Control Module (VCM) detecting an issue with fuel delivery or engine performance. This could be due to several factors, including a faulty fuel pump, clogged fuel filter, or issues with the fuel injectors. It's essential to conduct a thorough diagnostic to identify and resolve the underlying issue to ensure optimal engine performance.
FFS on a 1990 Cougar stands for feedback fuel system.
MAP sensor
As you do not list the code you are reading, it is impossible to answer your question.
In 1990-1994 XJ6 the VCM Code 44 is the code for the O2 sensor, either rich or lean exhaust has been detected and is causing the code to trigger. It could indicate a bad O2 sensor.
If you mean a low fuel light, then NO.
Ignition Amplifier Failure
this code means there is a problem with the fuel level sensor curcuit
I am running low on fuel
fuel injectors
Bank one fuel system rich.