Toiletduck34

i added a new fuel filter a few days ago. I ran the old fuel out with the pump and added about 5 new gallons, ran that through until it cleared out. it should be good enough to keep it running. Im leaning towards now the cold start sensor and the thermal switches. still trying to understand all these system. these sensors are ~50 years old, im sure they arent working perfectly. I think im to the point i know the engine is good. i want to tear this entire engine bay apart, clean, replace and start from fresh.

its not near close enough to get into the intake. I did test the injectors and they are coming up with 12V now. When i tested them i was testing while cranking thinking both sides would be (+, -) but both sides are showing 12v. 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. EDIT: RPMs shows, i can keep revs around 800-1000+ and it runs for 10 seconds then stops every time. I engine has warmed up and I tighened the all the hope clamps so gas isnt leaking out and it still runs. Maybe whatever cobwebs were cleaned out since its been sitting for 10+ years. will continue to read and troublshoot.

UPDATE: Thank you for that information. I have unplugged everything I could from the Neutronics device, though I'm not sure if it's affecting anything. However, I've made a big step forward: I can now get the engine running for a short period of time! I don't understand why, but hopefully it makes sense to someone here. Here's what happened: I decided to clean the cold start sensor. While I was putting it back on, a neighbor came over to talk, and I forgot to tighten the hose clamp that connects to the fuel rail. I started the car, and it ran—but with a fuel leak. If I tighten the clamp back down, it won't start at all. I checked the fuel return line to ensure it's flowing, and it's fine. When the engine does run, the RPM is very low. If I increase the throttle to approximately 1500-2000 RPM, it runs perfectly for about 9-10 seconds and then instantly dies. This happens every time without fail.

I tested the voltage going to the injectors and I'm getting right around one volt or less.

As advised by Zed head, I'm going to start my own thread to document everything I've troubleshooted while trying to get this car started. This is my first EFI car, and I'm learning as I go, but I believe I've narrowed the problem down to the EFI system. The fuel pump is running and generating good pressure within the fuel rail. I have found no leaks or vacuum leaks. The AFM (Air Flow Meter) appears to be working; I can see it moving while cranking. I checked the continuity at the ECU pins, and the readings are correct, one pin is slightly higher resistance but looks to be okay. Im not sure if the AFM has a connection that i can take off an clean. looks to be directly wired. The starter/injector relay on the driver's side is clicking over and functioning properly. I've installed a new ignition coil and verified that there is spark at the spark plugs. The car can start with starter fluid but will not continue to run without it. Beyond this, I am unsure how to check why the injectors aren't getting a signal. I'd like to avoid removing the injectors and disturbing the fuel rail for now. My main question is how to troubleshoot why either the injector relay or the ECU is not sending a signal to the resistors, which in turn should activate the injectors.

I live in arizona... i bought it and it just arived in less than 24 hrs. fastest turn around for a relay i thought i would have to wait 1-2 months for.

I just picked up a 1977 280z with a wiring harness for a "Neutronics" system. It looks like it connects to the o2 sensor on the exhaust and possibly the ignition coil. I cant find a single google search about this system or a wiring diagram. I have a black, red and green wire disconnected. Any help would be greatful. If more infomration is needed this is a EFI car. I am trying to get it started. can get it cranking but thats about it.

Thank you! I was about to order one from Lithuania.

Replying to this thread a few years later - The Bosch relays have become extrmely hard to find now and are being sold for $200+ if you can even find them. are there any solutions for this? I need to replace this relay to get my engine running but im planning on moving to a megasquirt system in the future.