1990 Mazda b2600 Engine missing

after a hour at my table i repaired the plug for now.i jumpered 1st and 2nd injector --2nd still not working---i am truly in the dark here.

Switch 1st and second wire connector and see what happens.

there is no way to make them reach.very short wiring harness

What about 3 and 4, are they interchangeable?

there is less than 3 inches of play on any injector cable from harness

Attach a wire to the unpowered wire of any of the injectors that are not working. Start engine and manually tap the attached wire to ground. Does the engine seem to perform better?

When using jumper wires as previously expained, did you confirm that the wire was attached correctly and you were able to get continuity between all the unpowered wires?

connected ground to dead side of 4 --started engine taped ground wire to frame truck run great or alot better for a second as i taped it tried to straighten up---at least the testng is finally getting somewhere thanks where do i go now?

The PCM is npt grounding the circuit. Check the unpowered wire for continuity to the PCM if you have not done so yet.

If continuity is available, the PCM is faulty.

Reconnect the jumper for the unpowered side between # 1 and # 2 or # 3 and # 4 and ensure they are well connected.

can you tell me how i do that-do i look for wire in harness at computer---unplug unit--atach a ground to frame in cab to wire from injectors and connect test light to dead side of 4th cyclinder?

Unplug the computer, ground the dead wire of 4th injector.
At PCM harness side with one end of test lamp attached to battery voltage, probe the harness for the same wire. If the test lamp lights up, continuity is good.

i connectedthe 1st injector ground to injector 4 ground side and truck runs smoothe --2 and 4 are working

i did as you said--getting light at computer after grounding 4 dead side and test light on harness in truck---getting green light

is it bad to run engine jumpered?

The PCM is bad.

It is ok to run the engine this way. Not going to cause any more harm than already there.

It would be below 100% efficiency but not far away, and you can continue using or if you wish, replace the computer.