Good afternoon,

I have a 1986 Nissan 300zx with a 1985 VG30E (non-turbo) I have been working on for a while now.
I was able to get the car to crank and I know I'm getting fuel pressure, spark, and the starter is working.
My issue right now is that the car isn't sending the pulse signal to the injectors.

I have checked the green relay on the passenger side by the battery and it is activating, I have changed the crank angle sensor and distributor as someone told me they control both spark and pulse.
I know that the ECU I have in the car is working as it came from a running car and the lights for diagnostics are on.

I can only think that the problem is coming from 1 of the following:
-The engine wiring harness is not connected properly to the main interior harness and ECU
-There is a grounding issue somewhere preventing the injectors from getting pulse
-The ecu got damaged at some point since being removed from another vehicle

If anyone has any other ideas as to where else my issue could be I would greatly appreciate it.
I would also like to know if anyone either has images of how the connections for the engine wiring harness should be inside the engine bay and inside the passenger area to discard any potential issues there.

Thank you!

You've ruled out the CAS, distributor, fuel pressure, and spark.

I've had the same issues.

Let's do the easy stuff.
Check the fusible links near the battery and make sure they are not blown.

Make sure the distributor is plugged into the correct socket, which is on the passenger side. There is the IACV plug that is on the driver's side that it will plug into, which is a common mistake.

Unplug the injectors and put some sort of light strip in the sockets, like xmas lights or an led strip. Crank the engine and see if the light pulses. If so, then you are getting a pulse. Check all 6 plugs if you can.

Check to see if the injectors click by putting 12v to them really quickly, not too long. You should hear a click. If not, then that may be the issue.
Make sure all of the ECU grounding wires are actually grounded. Should be 2 body grounds on the firewall, about 2-3 grounds on the plenum. Grounding is very important with these cars.

Does the car run on ether?

Unplug the MAF and see if the engines turns over and stays idling without it plugged in, bad MAF?

Ok so I already checked with the bulbs on the connectors to see if there was pulse.
I have a diagram for the connectors that told me the CAS plug was on the passenger side like you mentioned so that's out too.
I actually already checked the fuses, just in case 1 blew from any parts we were checking.
The injectors were checked and cleaned with a 9V battery before being installed, all 6 were spraying fine.
Additionally, we found that after disconnecting the battery, unplugging the ECU, and waiting for a bit before reconnecting everything, the car will get pulse on the injectors and can run for a few minutes normally, even reving without issue.
The car will run without much cranking if fuel is sprayed into the intake, after the MAF.

I will attempt to turn on the car without the MAF and let you know but I was separating the cable bundles of the engine harness to the ECU and found a few black badly spliced cables that, according to the multimeter, were ground. I'm thinking I will probably have to remove all the shieldings for the bundles, check all the cables, then re-shield them after fixing anything that looks wonky.

If you have any additional photo or diagram that shows the locations of the grounds, that would be awesome.

Thanks, and sorry for the long time before responding, this is a university project that is mainly worked on the weekends.

The diagram should be in the Factory Service Manual, under electrical systems, page EL200

According to that diagram, all my grounds are connected, the only weird thing is that connector 20f and 36f are going together into 1 grounding point for my harness.
Also what exactly are the Check Connector and Magnet Clutch, on my harness the Magnet Clutch Connector appears to be cut and, from what I found, the Check Connector is a diagnostic device dealers have.

thank you

Magnet Clutch is possibly the Air Conditioner Plug. My 20f and 36f also ground on the same spot on the plenum, That should be fine.

To be on the safe side, I went and grabbed some electrical wires and added my own ground from the plenum to the body.

Did you try to rule out a possibly bad MAF? Try disconnecting it and see if it will run on its own. As that was my issue that got my car to idle and run on its own

I have run 2 grounds from the plenum to the chassis.
I have also tried to run the car while the MAF is off and no luck.
Are there any other things I may be overlooking as going bad that may cause something like this; maybe fuel pressure reg is bad so injectors can't fire properly or a bad oil pressure regulator is preventing the system from working? I know that these are issues on some cars but I don't know if they would affect this car specifically.

So you're not getting injector pulse.

I forgot that you had swapped an '85 VG30E into your '86, which is perfectly fine if you kept the same exhaust setup with the o2 sensor for the '86 motor and the '86 ecu to run the new motor. IF you are using a different ECU, it may cause an issue because of the different specs of the ECU, for example, injector impedance and o2 sensor type. http://www.xenonzcar.com/z31/modelsearc ... Turbo+5spd

Also, were you able to put the ECU into diagnostics mode and see if there are any codes being thrown? http://xenonzcar.com/z31/ECUcodes.html

After putting the ECU into diagnostics mode, make sure you switch the ECU back into normal mode.

Definitely check to see if the fuel regulator pressure is working correctly. a leaky FPR may show in the vacuum port area.

im fairly sure my o2 sensor is the thicker one, i was not aware there was a potential issue there.
Could that cause no pulse?
The ecu is the same 86

i just installed a skinny o2 sensor, still no pulse

your assuming a clicking relay has good contacts still on a 1986 car ? Ether jump the NO contacts with wire to see if you SIMPLY need a new relay ?? Or spend the $ 18 if you don't know how to do it / can't substitute a "known "good one. A pitted/worn relay contact will have very very similar effects of "bad grounds" - 12V out of a relay is called "high side" , wires connected to ground are conversely "low side" , both capable of equally bad connectivity.

The relay on this car for the fuel should only affect the pump as the ecu directly goes and gives the ground signal to the injectors. The pump is definitely working and reads at 60-65psi before the regulator.
I am in the process of procuring an electronic pickup coil to make sure that isn't the issue and I'm still fairly sure the ECUs I have work, or at least 1 should.
On a side note, does anyone know if there is a problem with using 1985 injectors in a 1986 ECU and wiring harness car?

ok so i feel like an idiot, it seems the injectors were the issue.
I plugged in 1 injector I had from the 1986 engine, the only injector that worked from the 6, and it seemed to be working.

'85 injectors should work OK on the '86 ecu as long as its matching N/A injectors to N/A ECU. I'm glad you found the issue in the injectors. Make sure to test all 6.