35 minutes ago, Yarb said:

I understand that, AI is a smorgasbord of articles massaged into one

I almost made a comment about AI. It's basically a better Google search. But that's about it.

23 minutes ago, Toiletduck34 said:

, the injectors are all functioning and sensors because its stopping after a running for ~9 seconds

The engine can run off puddled fuel in the intake manifold. If the injectors were opening the engine would continue to run. cgcheen's suggestion about testing with a 9 volt battery was a good one. You can run separate jumper wires if you don't have an EV1 connector. With a 9 volt alkaline battery you don't have to worry about melting wires if you accidentally short them. You'll hear a click when you connect the 9 volts, if they're opening. Also, with 9 volts you can leave the voltage connected while you tap them. You'll have the solenoid pulling them open if you can get them to break loose.

Pin 1 at the ECU is the ignition signal that the ECU uses to monitor engine RPM. It's connected to the negative terminal of the coil. It should read battery voltage with the key on. But it also needs a certain type of voltage pulse. There are things that can screw it up.

You're making great progress.

I’ve mentioned it some many times in the past about replacing each and every connector on the EFI harness and cleaning each connection in that arena. You will be amazed at the corrosion that you find on each connector and the wire itself. I had to shorten some wire by over an inch before I could find wiring that was suitable to crimp/solder.

9 minutes ago, Zed Head said:

The engine can run off puddled fuel in the intake manifold. If the injectors were opening the engine would continue to run. cgcheen's suggestion about testing with a 9 volt battery was a good one. You can run separate jumper wires if you don't have an EV1 connector. With a 9 volt alkaline battery you don't have to worry about melting wires if you accidentally short them. You'll hear a click when you connect the 9 volts, if they're opening. Also, with 9 volts you can leave the voltage connected while you tap them. You'll have the solenoid pulling them open if you can get them to break loose.

Pin 1 at the ECU is the ignition signal that the ECU uses to monitor engine RPM. It's connected to the negative terminal of the coil. It should read battery voltage with the key on. But it also needs a certain type of voltage pulse. There are things that can screw it up.

You're making great progress.

That makes sense, I already testedt all the ECU pins and were reading correctly... The only thing left is the AFM which would also make sense why the injectors wouldnt firing. I tested each injector and they are functioning.

I have stopped testing for the night because i broke a fuel line that was very old. will need to replace that before messing with the AFM. but i dont think im getting good signal from the AFM to the ecu. thank you for your help everyone.

Here is a way to test the function of the injectors separately from the ECU. With the ECU connector removed from the ECU, turn the key on. Then short the pins in the ECU connector from the injectors to ground with a quick tap. Each tap should produce a click frm the relevant injector. You'll need a quiet garage or a friend in the engine bay to hear them. Or a long wire.

6 minutes ago, Toiletduck34 said:

I have stopped testing for the night because i broke a fuel line that was very old.

If you do get the engine running well, replace all of the old fuel lines on the rail and the injectors before too much driving. I smelled gasoline on mine one day while driving and when I opened the hood a tiny stream of gasoline shot by me on to the sidewalk. They dry out and crack lengthwise.

The small stuff will eat up a lot of your time but it's worth it once you're done.

Edited 19 hours ago19 hr by Zed Head

O.P., you should probably pull a spark plug or six and see if (how much) they are sooted up.

20 hours ago, Toiletduck34 said:

.... i can make it leak anywhere on the fuel rail and it seems to work. its really odd. i dont know how the fuel pressure regulator works but maybe i have too much pressure? Ill check the RPMs.

The Fuel Pressure Regulator (FPR) on an EFI engine is "vacuum referenced" or Manifold Absolute Pressure (MAP) referenced. Meaning it has a hose connection to the intake manifold. The FPR is supposed to maintain a fairly constant fuel pressure differential with the manifold pressure. Nissan uses 2.5 BAR or 36.3 PSI as the required differential. That means WITH the engine NOT RUNNING and fuel pump RUNNING the pressure to the fuel rail and injectors should ~36.3 PSI. When the engine IS running, the FPR will SUBTRACT the manifold pressure while under VACUUM or ADD the manifold pressure if under boost (positive manifold pressure). You don't need to consider boost. But, say you have 10 PSI of VACUUM while the engine is running at idle, your pressure at the fuel rail and injectors should be ~26.3 PSI (36.3 - 10 PSI).

15 hours ago, Toiletduck34 said:

Right now i believe ive rules out the fuel system, the injectors are all functioning and sensors because its stopping after a running for ~9 seconds regardless of its tempature, hot or cold.

The last thing for the ECU troubleshooting is the Tachometer. I am getting a signal from the coil at the tach, but i dont know if the ECU is getting that signal.

First: The ECU DOES NOT get the "tach signal" - that circuit if for the GAUGE ONLY. It is pointless to look for it. The Electronic Ignition Module figures out when to send a signal for the coil to fire - it gets the information from the distributor electronics (pretty sure - I haven't handled the original Bosch L-Jetronic for a blue moon...)

Second: Have you tried operating the engine WITHOUT the cold start valve? Disconnected from wiring and/or fuel? (IS your engine only running on the cold start fuel??)

I think im chasing my tail on this one.... This morning i repalced a few fuel lines as 5-6 started to leak and crack from the fuel pressure. I also used some electrical cleaner to clean all the electral connectors.

I started to engine and it can now run past 10 seconds without fail. not sure why. but great! the issue now is its running very poor. Rich and extremely low idle. I tried adjusting the AFM and idle adjustor but nothing is effecting it. I double checked the ECU connections and now im not seeing any ohm readings on the appropiate pins for the AFM and the TPS. I checked the TPS internals and connectivity is all there. it must be the wiring somewhere.

In the end i wanted to get the engine running and it is! so thats fantastic. I think im done troubleshooting this thing and im just going to leave it as is for the moment. I plan on replacing this entire ECU/AFM & fuel system anyways with megasquirt or similar system. No need to fix this system if im going to be getting rid of it.

Now its time to tear things thing down to the frame.