Land Rover Freelander fuel pump

Bizare as it might sound your pump is pulling so much it's creating a vacuum blockage,and yes I know how that sounds but for every say litre of fuel it pulls from the tank has to be repalced with air otherwise you create a partial vacuum,or negative pressure in the tank until it doesn't have the power to overcome the suck,so no fuel flow.the filler cap is meant to be vented so the air can get in,plus there's the carbon canister as well.
take the cap off anf see if that alters the running because somehow or other you need to have the used fuel volume replaced with atmosphere,oh and check the fuel lines for pinched bits,had one in once that would only run for precisely 4.2 miles,every time,turned out it had been jacked up at the garage with a poorly positioned leg which had pinched 2-3 inches of pipe.