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If there is injector pulse than the crank sensor has to be good. Injector pulse and spark are both calculated off from the signal from the crank sensor.
Checking for power and ground to the coils is a good place to start. If that checks out than either there is a wiring issue in between the PCM and the coils or possible the PCM has failed.
If ECU has crank signal and engine turns over, ECU should give injectors a pulse and trigger the ignition. If not ECU might be bad. You should check power and grounds going to ECU. There are usually multiple power and grounds going into ECU
Try to provide a ground for the PCM. Find the ground wire for the fuel injector circuit at the PCM connector and short it to ground. The PCM gives the injectors their signal, if it works and starts the vehicle, then you will need a PCM. If not, then it will be a wiring issue somewhere in the harness.
It may be time for a pro to look at it. You dont want to guess wrong on a PCM. Are you sure you have Injector pulse? One side of the fuel injectors should have power and the pcm grounds them to make them open. If the engine runs on carb cleaner its not getting fuel.
1991 this make you OBD1 . You can access a code by jumping 2 terminals together.The injector pulse is from the PCM . If you have no pulse you need to troubleshoot for spark first . If you dont have spark do spark first then injector pulse comes on. If no injector pulse check fuse in engine junction box.Use a volt meter check grounds at PCM. If all else checks out good replace PCM. You may also want to check the TPS. If this sensor short out in the WOT position you also wont get injector pulse.SO disconnect the TPS. and recheck for injector pulse
Spark indicates crank sensor, ignition coils and modules-ok
no voltage at injectors; should be 12v in each of the injector wires (not the black one) with key on engine off. Voltage provided to injectors comes from injector driver circuit inside PCM, and pulses ground signals to open and close injectors.
The first thing to check would be spark. This can be done by connecting a spark plug tester to a plug wire while the engine is cranking. The tester must be grounded to the engine block for a good electrical connection.. Your fuel pump pressure is OK. The problem should be electrical so check 1. No voltage to the fuel injectors (blown injector fuse or bad relay) 2. No pulse signal to the injectors from the PCM (no crank or cam sensor input to the PCM, or a bad driver circuit in the PCM, or awiring harness problem) 3. A shorted fuel injector (robs voltage from the other injectors so none will operate)
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