2011 d40 v9x non starter

Hi all I'm new to this forum hope I can help and be helped I have a nissan Navara 2011v6 auto diesel the thing just died on me 8months ago .to cut a long story short 2diesel specialists and £3000later still not starting. Took into nissan to be told needs a new fuel line and injectors cost £4800 and that might not be the cure. I don't think so::headshake looks like the fuel is not getting to the filter anyone know if there is a pump in tank::banghead:if not fuel is running back to tank:confused: heeeelp