280z starting problems

[dylancorrea1]

Why would he need a smoke machine, or a cigar?  He said it runs well once it warms up, enough to do "a lap".  All that seems to be here is difficult cold starts, and some dodgy work by the PO on the wiring.
Just saying, there's a risk of over-advising.  There doesn't seem to be a vacuum leak problem.
 

Car starts and stays on now, changed the fusible links, new battery, the fuel pump is a little low on the pressure but works, and messed with the idle a bit. Oh and also cleaned the grounds.


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[dylancorrea1]

I flipped a few of your pictures so I wouldn't break my neck[emoji3].
Overall the engine looks to be in fair shape and you've replaced some of the tune up components. That's why I asked if you had adjusted your timing. It's not too difficult to do and it's in the FSM. Assuming you put the spark plug wires in the proper firing order, I was wondering if the distributer had twisted a little.   Most everything is in the right place and the fuel and vac lines seem to be OK , at least from what I could see in your pictures, but check them for cracks and leaks anyway.  The fusible links  and battery connections will need to be addressed in the near future. I don't know what gauge the links are and there is a thick red one where a black one should be. plus the rusty alligator clip is not pretty, but functional.  Are you in the US?  Replacement fusible links and covers are easy to order .  All of those things I mentioned plus more affect the engine.  On a side note, maybe the PO was using the carpet mat as a fender cover when working on it? or is the car missing the hood vent cover,  either way, carpet mats don't belong in the engine bay.
Folks have given you good advice so far, but also use the search function for just about any question you have (it's all been done before and talked about).  If you look under the Resources tab at the top of the page,  you'll find lots more info and encouragement there also.
 

Car starts and stays on now, changed the fusible links, new battery, the fuel pump is a little low on the pressure but works, and messed with the idle a bit. Oh and also cleaned the grounds.


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[gwri8]

What is the current state of the battery connections?  Can you take pic of that and the fuseible links?  Maybe there is a fuel issue..The EFI harness powers off the battery with fusible links on the battery connections like these on the positive and negative cables.  How are you checking fuel pressure?  a lot of 280 owners put a fuel pressure gauge in line between the fuel filter and fuel rail just to keep an eye on fuel pressure every time the open the hood. 

[dylancorrea1]

What is the current state of the battery connections?  Can you take pic of that and the fuseible links?  Maybe there is a fuel issue..The EFI harness powers off the battery with fusible links on the battery connections like these on the positive and negative cables.  How are you checking fuel pressure?  a lot of 280 owners put a fuel pressure gauge in line between the fuel filter and fuel rail just to keep an eye on fuel pressure every time the open the hood. 

The battery connections are new, I had already gotten 2 new battery cables so the connections are clean and nice. I can update you with some better photos of the links tomorrow as of right now I’m out. I checked by attaching a line to the fuel filter, and disconnecting the starter solenoid, the gauge read at 20-25psi. There are no extra wires connected to my negative battery terminal. There are 2 white wires to my positive which go into the wiring harness under the fusible links, There is an extra red wire which I’m figuring out what it does that seems to run along into the the dash board area on the driver’s side, under the brake cylinder, and an extra red wire which runs under the car. I figure the one cable under the car that is currently hanging out is the previous owners bad wiring attempt at a Subwoofer which ruined a lot of wiring. The picture are the new links I installed.


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[dylancorrea1]

The positive cable is the one with the two white wires.

The skinny red wire I assume is their poor job at a subwoofer, and the thick red wire has a job and I’m going to be adding it to the positive terminal cable.


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[gwri8]

Bear in mind that electrical is definitely not my strong suit so I'll wait to see some better photos, but I'm going to guess that the EFI harness is not hooked up.  I can't stress enough that you need to know where each wire connects to.  Guessing can make HUGE mistakes and when you run into PO hacks, it makes it more difficult. Have you downloaded the FSM for you car yet?  If not, it's under the resources tab on the header or click here. https://www.classiczcars.com/files/. You can also get the color wiring diagram for your 78' there, also along with the EFI Bible.  These will give you a wealth of info, and in particular how things should be.

But basically, you'll need to find the EFI Harness and trace the wires.  It connects to the ECU in the cabin and comes into the engine bay through the firewall underneath the clutch master cylinder.  It splits from there and goes down along the frame rail and to up tothe fuel injectors.  It also goes  up and across the firewall over to the battery.  These are  the wires that should make connections to the battery.  They should be in a loom but it doesn't look like it and I'm going to guess that the loose wire that crosses over the hood latch in one of your photos is one of them. Maybe that other wire you suspect to be for a subwoofer might be part of that EFI harness also. Trace it to be sure.

[mayolives]

15 hours ago, dylancorrea1 said:

"I checked fuel pressure, and received about 20-25psi, I believe its supposed to be 36psi so I will be getting a new fuel pump." 

 Inexpensive fuel pressure gauges can vary in readings. 25 PSI isn't what you need but should not cause the problem you have described. Good quality fuel pumps are expensive so I would hold off on buying one until you can check a few other potential areas that may be bugging you. At some point you should double check you FP gauge with another one. 
 

 

[dylancorrea1]

Bear in mind that electrical is definitely not my strong suit so I'll wait to see some better photos, but I'm going to guess that the EFI harness is not hooked up.  I can't stress enough that you need to know where each wire connects to.  Guessing can make HUGE mistakes and when you run into PO hacks, it makes it more difficult. Have you downloaded the FSM for you car yet?  If not, it's under the resources tab on the header or click here. https://www.classiczcars.com/files/. You can also get the color wiring diagram for your 78' there, also along with the EFI Bible.  These will give you a wealth of info, and in particular how things should be.
But basically, you'll need to find the EFI Harness and trace the wires.  It connects to the ECU in the cabin and comes into the engine bay through the firewall underneath the clutch master cylinder.  It splits from there and goes down along the frame rail and to up tothe fuel injectors.  It also goes  up and across the firewall over to the battery.  These are  the wires that should make connections to the battery.  They should be in a loom but it doesn't look like it and I'm going to guess that the loose wire that crosses over the hood latch in one of your photos is one of them. Maybe that other wire you suspect to be for a subwoofer might be part of that EFI harness also. Trace it to be sure.

Thank you, I appreciate the response and the continued help with trying to get the car running in better shape. Electrical stuff isn’t my strong suit either, It can be quite confusing and very overwhelming. But I downloaded the color diagram for the wiring, and also the EFI bible which ill be reading through and running some of the trouble shooting methods and tests, I already had the FSM. I will trace down all the wiring and see how well of a job I can do with EFI bible and FSM and keep you updated, but yes I also believe the harness isn’t hooked up to the battery. Thank you for all the help with the car.


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[Dave WM]

fyi, another possible cause for low fuel pressure is clogged fuel lines, make sure your pump is not having to work too hard to get the fuel in the 1st place. the fuel should siphon thru the supply line when disconnected from the pump lnlet. If it does not you have a restriction. check this before popping for a new pump.

There is also the possibility of poor electrical supply to the pump itself (thru wire and relays), check the voltage AT the pump. There will be losses along the way but you should still see at least 10v with the key on, engine off, pump running. It will prob be higher if you test with the engine running (since the voltage will be closer to 14v at the battery. I tested my by observing the voltage key in start  engine off, using the start position with the solenoid disconnected to get the pump running using the start circuit. Make sure you have good solid hookups to the pump.

1975 Datsun fuel pump voltage drop - YouTube

 

 

Edited March 31, 2021 by Dave WM

[dylancorrea1]

Bear in mind that electrical is definitely not my strong suit so I'll wait to see some better photos, but I'm going to guess that the EFI harness is not hooked up.  I can't stress enough that you need to know where each wire connects to.  Guessing can make HUGE mistakes and when you run into PO hacks, it makes it more difficult. Have you downloaded the FSM for you car yet?  If not, it's under the resources tab on the header or click here. https://www.classiczcars.com/files/. You can also get the color wiring diagram for your 78' there, also along with the EFI Bible.  These will give you a wealth of info, and in particular how things should be.
But basically, you'll need to find the EFI Harness and trace the wires.  It connects to the ECU in the cabin and comes into the engine bay through the firewall underneath the clutch master cylinder.  It splits from there and goes down along the frame rail and to up tothe fuel injectors.  It also goes  up and across the firewall over to the battery.  These are  the wires that should make connections to the battery.  They should be in a loom but it doesn't look like it and I'm going to guess that the loose wire that crosses over the hood latch in one of your photos is one of them. Maybe that other wire you suspect to be for a subwoofer might be part of that EFI harness also. Trace it to be sure.

Also is there anyway to upload or send you a video of the engine running?


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[SteveJ]

13 minutes ago, dylancorrea1 said:

Also is there anyway to upload or send you a video of the engine running?


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https://www.youtube.com/

[dylancorrea1]

https://www.youtube.com/

https://youtube.com/shorts/OenZrP1w7Kw here the video you would like to take a look, it sounded a bit better yesterday and after it warmed up.


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