2000 Pathfinder losing power

[tmccar]

I have a 2000 Pathfinder with a .5L diesel engine. It loses power and revs after a few miles, and if I turn it off and start after a few seconds it fires up again and the revs come back slowly.
I tried changing the plunger unit over the fuel filter but that didn't help. what else could it be?

On a separate note (possibly), could anyone identify the cable in th photo with the yellow stripe? It it disconnected at the other end.

 

[Trevor]

Maybe there is still an issue with air in the fuel filter housing and as long as the primer is firm to push in then its okay if the resistance drops quickly and you find you have to pump it more to fill the filter then replace the primer and also the filter if it hasn't been done for a while. Start there and see how you get on

Black with yellow lead is an earth but where to no idea, unless its back to the battery negative directly.
On that note, check all earth leads are in tact and corrosion free as quite common fault on Nissans

[tmccar]

Thanks - I got a new primer pump and it didn't help at all. I could try a new filter, but I did change that one recently.