fuel hose size JX to AAZ conversion

[tattoojohnny]

Morning all
My diesel keeps syphoning back to the filter. The hose from the filter to the pump is old and brittle (clear plastic type) and barely reaches from the filter to the pump as has been trimmed before to remove a leaking end. Just wondering what size hose I need to order.
TIA

[Timburrows]

Same size as you have already got,check oring on filter, leak off pipes and return pipes for wet patches air in fuel out or it may be the pump throttle spindle leaking or you could fit a non return valve in the supply pipe,it won't fix the problem but it will stop the fuel syphoning back