Series 2A Diesel conks out after 5 mins

My Series 2A diesel starts every time but gives up after about 5 mins on the road. I've changed the fuel filter and checked lines from the tank. Its regular as clockwork and starts again after about 15 minutes.
Any advice would be much appreciated as I'm kind of stuck.

Thanks in advance.

possibly air in the fuel, which collects at top of sedimentor filter, does it help if you bleed it at the sedimentor and then the injector pump,

the leaks ive had causing similar problems have been on the fuel spill rail, tried new copper washers then PTFE tape which cured it