Ford Repair: 1990 E-250 4.9 fuel injection, fuel pressure regulator, engine cranks

Question
Dear Sir,  I am attempting to repair the vehicle purchased by a friend not running.  The engine was bad, and I have done a complete rebuild, but the original fuel rail and injectors were missing. I was able to obtain those parts from a salvage yard I use frequently, and which had several sets of these parts that came off of their service vehicles which were running when wrecked. My problem is that no fuel seems to pass through the injectors while trying to start the engine.  I can hear both fuel pumps run, and fuel is present at the fuel rail test valve, and when I disconnect the return line and crank the engine, I get about a half quart of fuel in 10 to 15 seconds.  I don't have a pressure gauge, so I swapped high pressure pump from an 87 model E-350 I own (parts vehicle), and have also installed a new fuel pressure regulator, but after cranking the spark plugs are powder-dry. A local Ford dealer tech guy said there should be a check valve in the return line which controls the flow, but the parts department lists no such part, nor does the book (Hanes) I used to rebuild the engine.  I don't have a way to check the injectors for pulse, but I did try swapping the EEC unit from the E-350 temporarily, to no avail.  My local parts store did not have a test lamp for this application.  I am no expert on late model fuel injection and may have missed something simple I suppose, but all wires look good, and the engine cranks normally and builds good oil pressure. Any suggestions are greatly appreciated.


Answer
Hello and thanks for the question...I'll try to help.
 What you could do is take a 12v test light and disconnect ALL of the injectors and check to see if they are getting a signal pulse from the PCM. Connect the test light to the positive side of the battery to perform this check. A blinking light means that the PCM is grounding the injector circuit and is doing it's job. Lack of a blinking light, means that the PCM is faulty or the wiring isn't complete.
As far as I know, there isn't a "check valve" located any where in the system for this vehicle. The only thing I can think of that the tech might be talking about is an anti-flow back valve, that was installed as a recall or TSB. It is to prevent the swapping of fuel from one tank to the other. The components that are involved in this system are....Fuel pump(s), fuel rail, injectors, fuel pressure regulator.
Hope this helps,
Erik