Some months ago I was having difficulty refuelling my Granturismo, profchristopher-green had a couple of suggestions, which seemed straight forward but like all things straight forward that turn out to be far from it.
Having taken out the fuel tank and pipe work along with various methods of testing, we discovered the charcoal filter within the breather tubes was the problem. Some £150 later, fuel is being delivered as normal.
We also discovered that the old unit was over 1k heavier than the new one.
I hope this may help any one else with a similar problem. Dave Jenkinson