I have a fuel loop set up for testing fuel pumps and adjusting pressure regulators, I would like to also test cold start valves and fuel injectors. I need to know what kind of voltage should be used to activate the injectors and/or the cold start valve for test purposes that would be as close as possible to actual running voltage. This is for D-jet with the 2.0 (green) injectors.

I wanted to domthe same, inwas thinking of 12 volts straight from the battery, I guest not!

From the Harold T Glenn FI book:

Thank you very much for that information Mr. Bowlsby...I can just see it now.........wondering why every injector I tested seemed to be bad.

Bosh recommends limiting the current to 2.8A through the injector.
In the car, the injectors are driven by a current limiting circuit that applies a higher voltage to open the injector and then reduces it just to keep it open. If I remember correctly, it opens it at 2A and then maintains it open at 1A.