Hello Phil,
I usually measure injector spill with the injector wiring disconnected & cranking for 30 secs & have yet to see one that doesn't spill any fuel.On my measuring tubes I usually see 3-4(about the same height as you're getting I would think) graduations after 30 secs cranking & usually look for a difference between cylinders. Usually an injector causing a problem starting(not the problem you have) will spill off an obviously greater amount than the others. When cranking usually the high pressure should be around 250-280 bar & when held at approx 2000rpm, approx 700- 800 bar. You would expect to get a max of about 1450 bar viewing live data on road test at full load.
Your low pressure sounds ok at 3.9 bar , usually they are around 3.6-4 bar.
Have you got a better description for your code as I don't usually see the "P" code using Autologic.I will see if I can find time tomorrow to check the description.
I have yet to replace an overlay harness & have always managed to clean up the rail pressure sensor connections, tighten them & refit ok, but after also reading Franks' article in Aftermarket magazine, it does make me wonder whether there is more to replacing the loom, than just corrosion as the L/Rover TSB suggests.
I have had my suspicions about the quality of remanufactured injectors lately & have recently had an issue with some that tested fine twice(with the starting fault still apparent) & 3 out of the four have been fitted to other vehicles since with no problems(not by me), yet the starting problem was sorted when I fitted a genuine set of Bosch factory reconditioned injectors.
Hope this helps, Regards, Andrew
p.s It might also be worth checking to see if there is anything floating around in the tank, that could possibly restrict the pick up, but a pressure drop should be noticeable on dynamic data when road testing if this is the case.