The one labeled "return spring " in this picture;
My pump doesn't seem to have it.
i know it's been opend before, as there are no safety wires anywhere.
I know it was running because the donor car had Tbelt failure, and broken cam.
Do I need it?
Doesn't look like Cummins thinks so...
What do you think? Or better, do you know for sure?
Pump # is 460 406 044, Volvo D24T
Pretty sure that's the fast-idle spring, on pumps so equipped.
If your particular pump doesn't have the fast idle lever you don't have it, or need it.
Good news
My car uses a water operated bit of junk to seize up and not deliver fast idle by not moving the external throttle arm.