I have been having an intermittent starting problem with my 2003 Doblo 1.9JTD
So far I have had the crank sensor replaced, the Glow plugs and control relay, I have read elsewhere that it could be a blocked Fuel filter, its a job I have not done before and I don't have a workshop manual, can anyone give me a quick guide on how its done ? and is it self priming
Thanks
Bobiskra

Assuming your 03 is the same as my 05 then, yes the system is self priming.
Something worth trying is the relay in the cabin fuse box - that was my problem when I couldn't get mine to start. I only had the owners small handbook and thought I had covered the electrics by checking the fuel fuses and relays in the engine bay fuse box. The handbook didn't have any reference to the relays in the cabin fuse box. I literally pulled the four relays off, swap the 2 that were the same type and plugged back it. Bingo, I could hear the fuel tank lift pump activating and it fired up first turn of the key.
Mine started off by spasmatically cutting out when it was cold and then wouldn't fire up at all unless I hand primed the fuel system in the engine bay. Car ran perfectly all the while the pressure pump could suck fuel up, but as soon as I switched the engine off, back to square one. Simply fix in the end but it did take some finding.