1978 280Z - Won't restart when hot, all interior gauges, fan motor, backlighting not working

[NocturnalEmber]

Well, for those of you watching the thread, I apologize for the delay. I got hit with a sinus infection and wasn't operating at my best, so it took me until now to find some motivation to get things done.

I took a video that I uploaded below of the car after I installed the fuel pressure gauge inline in between the fuel filter and rail.

The fuel pressure I believe is on par with what it should be, but you can finally see/hear the current state of things.  The picture of the fuel pressure gauge is after the car had been shut down.

 

EDIT: I'm very sorry for the shaky camera!

Edited October 23, 2023 by NocturnalEmber

[Yarb]

Pressure is fine.

[Zed Head]

On 10/18/2023 at 8:12 AM, Zed Head said:

Sounds like your AFM is not connected, electrically.  Might be that the connector/plug fell off of the bottom.  It happens.  You can can check via the pins at the ECU connector to be sure.

 

On 10/18/2023 at 8:25 AM, SteveJ said:

That sounds like a good avenue to pursue.

I still like this thought.  It fits your problem.  Get out the meter, crawl under that dash to get to those kick panel screws (one of them only needs to be loosened, not removed), and pop that ECU connector off.  If the ECU doesn't see it it doesn't happen.

[NocturnalEmber]

7 minutes ago, Zed Head said:

 

I still like this thought.  It fits your problem.  Get out the meter, crawl under that dash to get to those kick panel screws (one of them only needs to be loosened, not removed), and pop that ECU connector off.  If the ECU doesn't see it it doesn't happen.

 

I forgot to mention I did check the connection at the AFM physically, and it seems, well, pretty snug on there.  Would I still be able to probe the pin on the ECU connector plug with my multimeter and check for something like varying resistance by moving the AFM flapper?

Edited October 23, 2023 by NocturnalEmber

[Zed Head]

Actually you did mention it.  But it's not enough.  

Nissan produced a whole set of instructions for testing at the ECU connector.  It tells you that the wiring to the AFM is intact.  The 1980 guide covers everything back to 1975.

[NocturnalEmber]

@Zed Head I probed pins 6 & 8 per the instructions.  I know it says "approximately" 180 ohms, so I don't know if my reading was out of spec or not, but my reading was 205.2, and it fluctuated to 205.3.  Would you consider that within spec?

[Zed Head]

That's just one measurement of many.  You need all of them.  They're shown in the book.  Since you got a high resistance the next step would be to measure the same at the AFM itself.  The high resistance could be in the AFM or in the wiring harness and its connections.

 

[Yarb]

While you’re at it pull the afm off the bracket. Very easy to do and clean the contacts on the afm. Cut down some finger nail files they work well. These systems are an electrical corrosion nightmare.

[siteunseen]

Here's some quick cleaning spots that will help a lot. Metal files work good, fingernail files too. I have an old points file that works great. 320 sandpaper works. Blow it all out with an air compressor.

https://www.atlanticz.ca/zclub/techtips/electricalconnections/index.html

 

[Yarb]

With that reading you have you probably have a lot of dirty connections. You will probably find plenty of green corrosion. Corrosion is impedance and that will throw your readings way off causing the system to go crazy🤦‍♂️🤦‍♂️

[Yarb]

Hey Cliff there’s a red tag on the thermotime/temp sub harness. I believe it signifies between the two sensors so you don’t get them backwards. My harness is out and not going to be used any longer so I can’t reference it on the car. Any clues from the Librarian?

[NocturnalEmber]

Okay, so I followed the procedures in testing the AFM after I pulled it off the car.

I tried cleaning the pins with deoxit and some scrubbing action, and after that was done I reconnected the plug to the afm and had the same issue, no change.

The first test on pins 8 & 6 was 205.2

The second test on pins 9 & 8 was 114

Third test I disconnected the battery from the car and ran the positive and negative leads from the battery to the respective terminals the manual specified and probed the other two terminals with my multimeter and got 6.xx volts with the plate fully closed, and as I pushed the plate open, the voltage dropped. I wasn't able to reach in with my fingers and push it all the way but it got down to 2.xx volts as far as I could push it, and it had more left to go.

 

 

Edited October 24, 2023 by NocturnalEmber