Ramses100 wrote:So maybe some clever person decided to do the same?
Not too clever then, since the layout of the 6.0's fuel lines is fundamentally different from the 5.3's and wouldn't benefit from this 'modification'
The 5.3 engine indeed features an A/C-driven fuel cooler to prevent vapour lock.
Clearly distinguishable in the engine bay of my XJ-S: it's the component between the LH air filter box and the LH intake manifold.
My best bet is that the botch was applied to circumvent a faulty climate control ECU, but your guess is as good as mine.
Our local heatwave is to test this assumption: disconnect the signal wire from the oxygen relay and see what happens...