LDV Convoy Minibus 2.4 Transit Duratorq engine

[LDV_Convoy]

Help!
I'm I'm having on-going issues with air leaking into the diesel fuel filter when left overnight or when left running on idle for >15mins.
Once driving its fine drove it 20+ miles the other day, not used alot as motorhome conversion in progress.
Having to top up the fuel filter with diesel and bleed the injectors to restart.

So far I have fitted a new fuel filter housing/filter and replaced the rubber fuel hoses that come off the top of the fuel tank as these were perished ( 3/16 return and 5/16 feed line).
The rest of the fuel line is in 8mm & 10mm i.d Nylon tubing with quick disconnects at the fuel filter housing and fuel pump. Need to decide do I replace with Nylon or rubber fuel lines and although I can buy both types of fuel lines locally in the UK I cant find UK suppliers of the quick disconnects with the technical info to get the correct sizing for Nylon or rubber tubing.
Anyone know of a good UK / European supplier of the quick disconnects or have any suggestions for narrowing down the leak prior to changing all the lines?
Cheers

[Penelope Stopit]

Has it got a hand pump for bleeding? The pump may be causing the problem

[LDV_Convoy]

It does have a hand priming pump on the top of the fuel filter housing its built into the assembly.
I replaced this unit as I suspected being 16years old it may be the source of the leak, but made no difference.
Its a transit engine and the fuel filter is a transit assembly