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

[siteunseen]

You can pinch the fuel hose between the filter and the fuel rail. Should be hard if it's got proper pressure.

I think you have fuel problems too. Sounds very familiar to what I had. A filthy fuel tank.

Do you have a clear filter coming out of the tank? You need one to see if there's trash in the tank. Fram G3 works best on the 280.

[Zed Head]

Didn't you check fuel pressure using a temporary gauge in the past?  And it was correct?

If it was mine, I'd pop the cover off of the AFM and make sure the vane is moving with air flow.  Simple stuff, no tools required.

Any chance you could summarize everything you've done so far with measurement numbers ?  Too many pages to go back and read through them all.  I see suggestions that I'm pretty sure have already been made.  Plus your problem is different now.  The title says "when hot" but now it's when cold.  The main problem has changed.

8 hours ago, NocturnalEmber said:

Unfortunately, the main problem hasn't changed.  

 

[NocturnalEmber]

1 hour ago, siteunseen said:

You can pinch the fuel hose between the filter and the fuel rail. Should be hard if it's got proper pressure.

I think you have fuel problems too. Sounds very familiar to what I had. A filthy fuel tank.

Do you have a clear filter coming out of the tank? You need one to see if there's trash in the tank. Fram G3 works best on the 280.

I do indeed have the Fram G3 inline coming out of the tank. Gas looks perfectly fine.

 

38 minutes ago, Zed Head said:

Didn't you check fuel pressure using a temporary gauge in the past?  And it was correct?

If it was mine, I'd pop the cover off of the AFM and make sure the vane is moving with air flow.  Simple stuff, no tools required.

Any chance you could summarize everything you've done so far with measurement numbers ?  Too many pages to go back and read through them all.  I see suggestions that I'm pretty sure have already been made.  Plus your problem is different now.  The title says "when hot" but now it's when cold.  The main problem has changed.

 

I did, and it was correct, but I thought there wouldn't be any harm in re testing.  The Airflow meter's cover has fallen off on me numerous times when I got the car to first start, so it wasn't held on there by much, and I think in the for sale pictures when I bought it the cover wasn't on and the vane was exposed. So it could have been tampered with? 

To summarize:

When I got the car I replaced the following with new parts:

Fuel Injectors & seals.

New aftermarket fuel pump. 

IGN ignition coil

Distributor cap

Plug wires

Plugs

Soft fuel line from tank to pump and from pump to hard line. (5/16")

Fuel filter in engine bay

Soft line from and post fuel filter inside engine bay. (5/16")

All fuel injection clamps have been replaced, no leaks.

fuel injection relay (under the dash) has been replaced with new at SteveJ's suggestion. (I measured voltage numbers with key ON/Off at the plug for the fuel resistor under the dash as SteveJ requested, and all of those I believe were within spec, hence the replacement of the relay.)

Fusible links on passengers side strut tower have been replaced with new.

Ignition Switch has been replaced with new (Beck Arnley.)

Oil Pressure Switch has been replaced with new Beck Arnley unit.

 

I also went and replaced ALL of the fuses on the passengers side kick panel.  Every single one tested fine with a fuse tester, but on closer inspection, they were almost all oxidized internally and I suspect this was building up resistance and heat because when I replaced them all with fresh, new fuses, problems went away (some of the three pod gauges in dash started working), my BRAKE light in the dash went from being dim to full brightness.) Turn signals started working, etc.  I suspect these old fuses were causing extra resistance because of how old/oxidized they were.

Fuel pressure has been verified as okay, but I am retesting on the off chance the gauge could have just been inaccurate.

So my current state of affairs are, the car will start when cold. Sometimes with no effort at all but a key flick, sometimes after some cranking. When it does start, it will run like it doesn't want to be ran (can only rev by a few hundred RPM regardless of how much throttle is applied, and generally once its been running for a few minutes, if you touch the gas or shut it off, it won't restart again until for a few hours.) 

On the bright side, all the gauges now seem to work and respond as they should, and the car will start on its own without any kind of starting fluid, but its just..rough when it does.  Plugs have maybe (on the extreme guessing side) 30 minutes of runtime on them and are all black.

 

I have no idea if it's misfiring, if the distributor timing is off (though it looks secure), or what.  I've checked the grounds, to my knowledge they all look clean and snug.

[Zed Head]

38 minutes ago, NocturnalEmber said:

So my current state of affairs are, the car will start when cold. Sometimes with no effort at all but a key flick, sometimes after some cranking. When it does start, it will run like it doesn't want to be ran (can only rev by a few hundred RPM regardless of how much throttle is applied, and generally once its been running for a few minutes, if you touch the gas or shut it off, it won't restart again until for a few hours.) 

I hope it's not so but that sounds little bit like a bad ECU.  When it's running poorly do you smell raw fuel from the exhaust?  One test/fix that people do is to bang on the side of it while it's acting up.  There can be broken solder joints inside that lose connection.  A few kicks or knuckle raps can remake the connection.  It's not a permanent fix but it's a clue.

Could also be the ignition module.  The clue there is the tachometer needle.  Does it jump around or read higher than it seems it should?

[NocturnalEmber]

8 minutes ago, Zed Head said:

I hope it's not so but that sounds little bit like a bad ECU.  When it's running poorly do you smell raw fuel from the exhaust?  One test/fix that people do is to bang on the side of it while it's acting up.  There can be broken solder joints inside that lose connection.  A few kicks or knuckle raps can remake the connection.  It's not a permanent fix but it's a clue.

Could also be the ignition module.  The clue there is the tachometer needle.  Does it jump around or read higher than it seems it should?

 

I wouldn't say I smell raw fuel in the sense of it smells like gas coming right out of the pump.  The car doesn't seem to smoke at all (especially not black smoke) but the exhaust does smells. This isn't a rotten egg smell like a bad cat, it just smells like..strong exhaust.   I just chalked it up to the car being 45 years old with a lack of emissions standards and it running poorly.

 

The tach definitely doesn't jump around, but I want to say a time or two it seems like it got stuck around 500 (when I turned it off it took a bit of tapping to have the needle drop.) 

 

I don't remember it doing this recently, though.

I'll give it some shaking and rapping on the ECU cover and see if that makes any difference.

 

Edit: On the off chance the ECU is suspect, Would a second hand one be a safe bet? I noticed they can still be had new..which is surprising.

Edited October 16, 2023 by NocturnalEmber

[Yarb]

Be interested to know where you found one that was new. I’ve seen refurbished but not new. Interesting.

[NocturnalEmber]

1 minute ago, Yarb said:

Be interested to know where you found one that was new. I’ve seen refurbished but not new. Interesting.

Looking into it closer, they are refurbs.  I've noticed some distinctly have less pinouts than others; Assuming the ECU ends up being what is at fault, am I limited to a certain model year, or are any  280 Z/ZX ECU's compatible ?

[Yarb]

There is a p/n on the side of the ECU. The plastic cut out I believe reveals the label. There is a post here on the forum on listing the compatibility of the units. I still think you need to get out the FSM and check each value of the readings. There’s no guarantee you will get a good refurbed unit.

[siteunseen]

 

 

[NocturnalEmber]

9 hours ago, Yarb said:

There is a p/n on the side of the ECU. The plastic cut out I believe reveals the label. There is a post here on the forum on listing the compatibility of the units. I still think you need to get out the FSM and check each value of the readings. There’s no guarantee you will get a good refurbed unit.

I think I'll break out the FSM and go over it, I know I remember seeing the page for testing the ECU pinouts with a multi meter, I just have to find it again.

Edit: Yeah, I did read that the ECU's are the same and the extra pins aren't connected to anything.

 

9 hours ago, siteunseen said:

 

 

Much appreciated! I do remember coming across that thread and I think someone suggested they were all compatible, but I was skeptical because the earlier ones I believe distinctly lack pins on the ecu side plugs itself.

Edited October 17, 2023 by NocturnalEmber

[NocturnalEmber]

I took a look at the AFM vane and thought I'd snap a picture in case it tells a story for anyone.  Nothing looked out of place (to me), but I've only worked on a total of three cars in my life that have utilized an AFM. The large grey piece and its respective component moves smoothly back and forth when you apply pressure.  Just seems kinda weird how theres three copper prongs that just don't move or go to anything, though.

[NocturnalEmber]

Another random sidenote: I replaced the green fusible links today (the ones on the harness near the battery) with ones I got from Zcardepot.  Does anyone happen to know of a better supplier for these? They lack the locking tab on the ends of the fusible links and as a result they come loose from the connectors very easily.

 

I'm really worried about these just dislodging from the connectors and breaking the connection when the car becomes roadworthy.  So if someone can recommend a place I can buy the oem green fusible links on the wiring harness near the battery that have that locking tab to hold them in the factory plugs, that would be awesome!

 

  The car has come a long way since I have gotten it, but this running issue is definitely a tough one.

Edited October 17, 2023 by NocturnalEmber