Hi we had the same problem with the GU Y61 TDI .
we changed the fuel pump $2500 ( no fire )
we changed the glow plugs $125 ( no fire )
then my father lost all his keys Nissan wanted
$1500 to transport the Nissan 450ks to there shop and also wanted $400 per key
I brought the id41 chips and a few keys and programmed two keys to the y61 after programming the keys I thought I would wind it over all of a sudden it started first kick every day for 3 weeks now it has started first kick ever time .
You might have the same problem hope this helps