I only ask for vehicle make /model/year and diesel system make / pump number because without this we are peeing against the wind, the pump may look the same as the next vehicle to it but the control actuation may be totally different. Injection pumps will have make and pump numbers on them , they could/ will be hard to read but they are there.
Information on diesel systems will be difficult be obtain because not many suppliers other then the makers of diesel fuel injection equipment have it, or understand it. Autodata is ok for general workshop info but usually limited on diesel info, Bosch ESI would be better for diesel but this only mainly covers Bosch.
Advice on suppliers of diagnostic equipment, there are not many you can trust and usually will only demo it on something that is covered by most serial tools. The best tool is the one between your ears over 80% of my work is done without the aid of serial tools (they tell lies). Try to work on vehicles that you have tools and equipment for and turn away the rest (for the moment).
As you have found out the spending never stops on newer tools for this and that, a good set of diesel low system pressure gauges will cost approx £1200.00. We have built our own over the years and are now building up another set (£400.00 for gauges and bleed valves without adaptors for vehicles).
You may be better off staying away from the older diesel systems, these are a lot more complicated then the newer CR systems (apart from some of the electronic sensors) and concentrate of just CR.
The biggest enemies of diesel fuel injection equipment old and new, is dirt, air and free water (plus ADD F) but I won’t go into that.
Air in older systems will throw up all sorts of surprises , so basic check is good supply and unobstructed return of the diesel fuel.
NEVER trust diagnostic tool sales people most haven’t a clue about real world work and the technical helplines for most are at best, basic.
Martin
Do the Bosch VSD 12 course with Mark and ask him lots of questions (I believe wine gums may be of use).