Originally Posted by Grant Francis

Return .line blocked would give excessive pressure and cause lots of running issues., normally. In your case I reckon "flooding" and that is stopping running, I think???

Trace that hose to the spigot at the firewall, remove that hose and put the end in a jar. Switch ON the Ign to prime the rail and ensure you have flow that far down the line. If so, read on, if NO then the issue is possibly in the fuel cooler (I remove the fuel lones from them on ALL my V12's and 6cyl)

If tht test proves OK, then its time to get "down and dirty" with the beast, and follow the steel line towards the rear of the car. LOOK CAREFULLY around the jacking points, as tyre fitters are reknown for jacking cars wherever the pads hit, and crushing that line, I have had a number like that.

There is a hose in that line where it travels OVER the rear cradle, usually leaks fuel, but it may have collapsed internally and plugged itself. PITA to do with the cradle in the car, but doable all the same. You will need that warped sense of humour, and that whole new language you are learning quickly, haha.

In the boot, front corner, LH side, obviously, is the end of that pipe/hose, and it twists around to enter the tank in that corner. Usually no issues with that hose, as the Spare Wheel protects it very well.

Take your time, one section at a time.